Iain's post gets at the heart of this thread, and there really are some valid but juxtaposed views to this subject, IMO.
There are people who play important roles in history by being 'the grain of sand that irritates the oyster," to quote that old goat Ross Perot. They become the MLKs, the Ghandis, etc.
But on an individual/psychological level, the numbers of young people searching for causes is staggering. Our culture rewards the successful 'cause' person. But Americans definitely have a false sense of security about what can happen in other parts of the world, so we end up with situations like those Amy Biehl and Lori Berenson found themselves in. Totally different people, places, etc., but a common thread.
When I was at UT-Austin in the early 80s, a reporter for the school's daily crossed the border to do an 'expose' article about mistreatment of workers in Maquilladora plants. Eight hours later, after the local authorities reportedly 'interrogated' him with a cattle prod to his balls, this guy hustled back to Austin having learned, I assume, a life lesson.
I think as a culture we need to reward 'cause' people for good works, particularly done at home, instead of protests (particularly abroad). As a parent, I will be doing everything I can to urge my kids to act as polite guests while traveling, and to keep their wits about them...I hope and pray they'll listen to me.
Go ahead, let the spray fly.