Since that's where the lobbyists line up for favors.
I've run into this a bit while looking into Jack Abramoff and SunCruz, and though I don't understand all the fine points, it's clear that there's considerable money involved in the regulation of the cruise ship industry. For example, here's something from 2000 about a Commerce Committee hearing on changing the laws regarding foreign-registered cruise ships. (If nothing else, seeing McCain's name as chairman and the mention of Carnival Cruise Lines, I'm reminded of that sex(?) scandal involving McCain and the female lobbyist that briefly surfaced earlier this year.)
http://www.congress.gov/cgi-bin/cpquery/R?cp106:FLD010:@1(sr396)
UNITED STATES CRUISE VESSEL ACT
R E P O R T
of the
COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION
on
S. 1510
SEPTEMBER 6, 2000
JOHN MCCAIN, Arizona, Chairman
TED STEVENS, Alaska
CONRAD BURNS, Montana
SLADE GORTON, Washington
TRENT LOTT, Mississippi
KAY BAILEY HUTCHISON, Texas
OLYMPIA SNOWE, Maine
JOHN ASHCROFT, Missouri
BILL FRIST, Tennessee
SPENCER ABRAHAM, Michigan
SAM BROWNBACK, Kansas
ERNEST F. HOLLINGS, South Carolina
DANIEL K. INOUYE, Hawaii
JOHN D. ROCKEFELLER IV, West Virginia
JOHN F. KERRY, Massachusetts
JOHN B. BREAUX, Louisiana
RICHARD H. BRYAN, Nevada
BYRON L. DORGAN, North Dakota
RON WYDEN, Oregon
MAX CLELAND, Georgia
Subject to certain limited exceptions, the provisions of the law known as the Passenger Vessel Services Act (PVSA) (section 8 of the Act of June 19, 1886) and section 12106 of title 46, United States Code, provide that only those vessels built in the United States and continuously owned by U.S. citizens and documented in the U.S. may transport passengers in the coastwise trade of the United States (between U.S. ports). The law was enacted in a time when maritime transportation was a significant mode of both domestic and international transportation. The law was intended to prevent U.S.-based companies from facing strong competition in the domestic market from maritime nations such as Great Britain. The law did not address vacation cruising as no market existed at that time. ...
Following World War II, the nature of maritime travel changed significantly as both domestic and transoceanic flights became more common and affordable. Air travel provided new competition for passenger vessels. With dwindling passengers, some vessel operators started to package cruising more as a vacation at sea than a mode of travel. By the mid-1970's the last regularly scheduled transoceanic passenger service had ceased.
Companies had to do something with now-empty ships. Cruises to a few tropical ports slowly became popular. The first passenger ship specifically built for warm-weather cruising was introduced in 1970 by Carnival Cruise Lines. From there, the industry grew rapidly and has boomed since the mid-1980's when the first megaships were introduced to the market. ...
S. 2507, the United States Cruise Ship Tourism Act of 1998, was introduced by Senators McCain, Thurmond, Hutchison and Burns on September 22, 1998. The bill would have allowed foreign-built vessels to be reflagged as U.S. vessels and engage in domestic commerce, and permitted limited employment of foreign-flag cruise ships in the domestic commerce. S. 2507 would have allowed foreign-built cruise ships, fewer than ten years of age and at least 20,000 gross tons and with accommodations for at least 800 passengers, to be reflagged as U.S.-flag vessels to engage in foreign commerce. The bill would have limited each company that utilized the provisions of the bill to no more than three vessels, and would have waived certain design and safety standards provided that a Coast Guard-recognized classification society had approved the vessel.