Cost of travel, food, hotel, the view from the hotel, and ogling along the way, are NOT considered compensation. Period. The invitee is not monetarily richer afterwards, and life experiences are not monetized. You don't like it? Take it up with the NCAA.
Also, NCAA allows competitions and try-outs during the summer, between the end of one academic year (spring) and the start of a next academic year(fall), as long as he's not paid for any of it.
These facts set aside, it might be argued that a college athlete gains in "brand", in marketing value, by participating in world championships. However, if that's your beef, then you should be ranting about the NCAA's BCS and March Madness, which are out-and-out money making enterprises built exclusively on the backs of NCAA-restricted amateurs, with only a few select athletes gaining in market value at the end (while assuming all the long term risk, from possible injury). Track world championships and the Olympics are no longer so craven. They remain a worldwide competition centered on a representation of country - now largely independent of amateur/professional status.