I'm hearing the same from my adcom this season. They are scratching their heads at why this foreign travel to "help people" suddenly seems from the applicant perspective as a required element of the application.
My guess is that applicants think that it will demonstrate several potential things about them:
1) social/global awareness/interest in the vein of another volunteering activity;
2) international experience (some schools, particularly NWU, love study/work abroad experiences, and this might suffice);
3) perspective (both by living in another country and learning to tolerate other views and cultures, as well as the troubling healthcare situations in other countries which even just as a comparative matter may be good to personally observe);
4) an interesting experience which will likely yield plenty of fodder for secondary essays;
5) an experience which not everyone has the time or resources to do, and which may help set them apart (however, given your response above, obviously this is
not an unusual experience); and
6) perhaps the advice of pre-health advisors? (this one I'm just guessing at).
Anyway, I did not undertake such a mission, but I am envious of those that have. I don't kid myself thinking that I would be doing more good by going than my plane fare alone would provide, but I do think that I would benefit personally from such an experience. In fact, I would love to go abroad at some point during medical school (but hopefully at a point where I could be of more usefulness).
Regardless, I completely agree that such an experience would ring entirely false if done without local community service to back it up.