To me, comparing destinations inside and outside of the US is apples and oranges. The safety, ease of travel (customs, etc.), and medical care in the US really can't be compared with reasonably close tropical destinations like Mexico and South America.

Even US territories like St. Thomas are plenty dangerous. I had a buddy go on vacation there and his first day, the restaurant he was eating at was robbed at gunpoint by a group of masked men... worse yet, none of the workers seemed surprised. Probably a decent chance they were in on it.