Are picky prejudices against "adult" foods/tastes immaturity or lack of cultivation?
So I enjoy very occasional cooking my family recipes for a few friends. These recipes involve olives, onions, tomatoes, and these particular items have been anathema to one or another guest. Today I'm having somebody over who had previously picked out the cooked tomato bits out of the dish. This time I asked ahead of time whether green olives are on the proscribed list, and sure enough, it was quite clear that they are. Fine, so I'm leaving them out until after that serving, then will add them into the rest. One time somebody didn't mention being a vegetarian and also did the picking thing, picking out the chunks of meat, although I know there are some even more gung ho vegetarians who won't eat the dish that had meat cooked in it but removed.
Well, full disclosure: I guess that I sneer when MY foods are shunned, but I have a long list of my own of non-edibles, and probably am WAY provincial, actually no "probably" about it. I guess I'm just baffled when my limited cooking has the kink thrown at it of ruling out my main ingredients.
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I see an awful lot of "adults" behave like spoiled children when it comes to food, especially in social situations. Yes a good host makes an effort to be considerate of guests' food preferences, but are there good guests any more? People seem to treat their picky ass PREFERENCES as life-and-death allergies and you know it is all jsut LOOK AT MEEEEEE bullshit.
I was taught to eat what was made and say thank you.
Spoiled westerners traveling in poorer countries piss me off the most. Just STFU and eat what is in front of you, somebody may have sacrificed a lot of their meager income to be hospitable to you! Or go on a cruise if indulgent food is all you care about. ugh 
Just eat the three bites that indicate you tried it and then complain of a mild tummy ache to explain away the lack of appetite for the dish.
When going out to eat however, you're paying for the meal and can be as picky as you like. If you're paying for the meal you can do what you need to do about staying way from foods that you don't like or that you're allergic to.
But some people are just stubborn about trying anything "new" and then they are just being immature and/or refusing to act like an adult by exploring new possibilities.
And yeah, for some people its a lack of cultivation - kind of like suggesting Olive Garden in NY city when asking about restaurant suggestions.
Oops! Did I really go there?! 
I'm going to a potluck on Sunday, and it has been mentioned that someone in the host household is allergic to peanuts. Therefore, I will not make my gado-gado (Indonesian steamed veggies with peanut sauce) for them but will find an alternative. No big deal.
However, if someone with a peanut allergy came to my house and didn't warn me ahead of time, and I made gado-gado as my main dish, it would be unpleasant for both of us.
So someone who has a strong food preference (vegetarian, allergy, celiac disease, keeping kosher) as a opposed to a whim ("I hate mushrooms"
, it is only fair to the cook to say something ahead of time rather than make a big production number out of refusing the food. If it's only a preference, just choke down whatever is set before you, taking only a small portion if the food is really repulsive to you.
For the record, I find shellfish repulsive. I'm not allergic, I just think they're tasteless and rubbery. But once when I was in high school, we were invited to the home of some friends of my parents, and the main dish was a proudly prepared oyster stew. The glares my parents gave me made it clear that I would have to choke down at least a ladelful of the stuff. So I did, and I have managed to avoid oysters ever since.
Food allergies are serious.
Tomatoes are related to deadly nightshade, from which belladonna or atropine comes from. So are tobacco and eggplants.
I am allergic to tomatoes and bell peppers and shellfish. I figured this out when I ate pizza in high school and it came back up an hour later.
The last time I had some chopped barbecue, the tomatoes in it set me off and I spent two days in bed in agony barely able to crawl to the bathroom because of that firey rear. I read labels because tomatoes are in a lot of foods, like all beef soups.
My grandmother regularly traumatized me at mealtimes by trying to insist that I eat what she fixed. She argued and argued. She cooked bitter greens and other boiled-to-death southern cooking. I wouldn't eat her metallic tasting black eyed peas. She was a home demonstration agent for the State A&M Extension Service for years, and kept lecturing us about the vitamins in foods. We said, "If you boil it to death, there aren't going to be any vitamins in it." That just pissed her off.
She tossed it in a pot and turned it on high because she was always in a hurry. She was a bossy bitch with an overactive thyroid who thought everybody else was lazy because we wouldn't get up at 6:30 am to do all those nonexistent farm chores she insisted had to be done. She was not living on a farm but thought she had to feed farmhands and load up our plates. She loomed over me and shook her finger in my face lecturing me. My mother loomed over me too.
She did her damnedest to make me have an eating disorder. I just said no. They basically said I was a bad person for not eating her crappy cooking. She and my mother tried to get me to eat raw tomatoes, bell peppers(green, yellow or red) and raw onions. Guess what? I can't eat any of those things decades later. I didn't know I had food allergies then. I just knew that I have to avoid a lot of foods and some things I just don't like and can't stand.
I love sautéed onions but raw ones give me an upset stomach.
I have known people who had parents who made them eat everything on their plates. The result? People who are obese and have learned to ignore their body's signals telling them they are full. My mother and grandmother whined constantly about how I didn't eat enough to keep a bird alive and I was going to starve. I didn't.
I refuse to overeat to make someone happy and I had some in-laws I told that to once at a family holiday. They gave me dirty looks when I said "I'm not going to make myself sick just to make you happy."
A couple of times other people have urged me to eat more and I burst into tears, because that is one of my hot buttons.
Anytime hubby cooks anything I am allergic to, I can't stand to be in the kitchen. That includes shellfish & smoked oysters and gumbo, or anything with tomatoes. I can't stand the smell of cooked spinach or asparagus.
I was grown before I found out that raw broccoli was good. I had never had it growing up. I did not have Chinese food until I was a junior in college, because my father refused to go to Chinese restaurants. I did not go to Benihana until I was in my thirties.
I had a mother in law once (2nd one, not the one previously mentioned) who cooked things I literally could not eat because they were greasy and spicy. One bite and I ran to the sink for water and she looked at me like I was some kind of idiot.
Restaurant food has gotten spicier over the decades and I really have to watch what I eat. Famous last words: "No, that's not spicy. It's fine."
That's too bad if someone cannot eat tomatoes, but I understand completely.
or clean your plate, etc... adults should be able to eat in peace without ridicule or guilt. When we invite guests into our homes, it's our duty to be good hosts. I think it's perfectly acceptable to inquire as to preferences. 
guests should be gracious. Maybe common courtesy and etiquette have become antiquated, I don't know. I do know I'm the only person who brings a hostess gift or writes out 'Thank you' cards anymore.
You did your best, and I hope you don't less this experience bug you too much.
It's being a control freak.
"If you don't eat my food, you don't love me and you are a bad person" is quite common in families and it's pretty sick. I got shamed for my eating pickiness and my allergies, although I didn't know they were allergies at the time.
I have seen the "supertaster" concept, and I think it applies to me. Supertasters can tell the diff between sugar and saccharine. Other people can't. The grandmother kept saying "It tastes just like sugar! It tastes just like sugar!" when they made me put liquid saccharin in my tea, and I kept saying "No it's not! No it's not!" because it was bitter to me. Just the kind of mindfuck I needed, where the parents tell me that my perceptions are WRONG WRONG WRONG. 
I remember going to a group meeting where after the meeting, they went to a Thai restaurant and I could not eat spicy food. They refused to change this and eat someplace else. They met regularly. So I started bringing a burger and fries to the meeting and eating there.
Then there was the time I went to a Thai restaurant with a group of people and I told them woman next to me I couldn't eat spicy things.
She asked, "Do you have a physical reaction?"
I said, "Yeah. I THROW UP."
She turned away with a disgusted look on her face.
I don't know what she was expecting me to say.