Norad - I'd wager that you place your life in greater danger by trying to move a disabled climber down from 27,000 feet than you do by asking a homeless person if they are okay and then calling for medical care if they are not. My guess is that most people are either afraid of/disgusted by homeless people.

I use "you" generically here.

(And - to be clear - I don't have a quick and easy solution for solving the homeless problem - I just raise it because I think it shows that there is a continuum of "not caring about other people enough to do anything about it" and that almost all of us are somewhere in that continuum and not at either end of it.)