We are social creatures, and we do certain things because we've been taught to. We look to others to see what they're doing before acting. In fact, when one person starts to help out, it isnt long before others jump in as well. It's not that we as people are bad or uncaring, it's just that we're waiting for cues from others. When we dont get the cues, we dont feel as if we need to step in. Or we feel less responsible because there's other people around. It's easy to look and say we'd step in, but as the show 'what would you do' has shown, in a lot of situations, most people dont step in. It's different when there's an obvious and clear situation and you know you should step in, and when there's a whole bunch of people around and you're not sure what the right thing to do is.
I think it sucks when people don't help others in need, like that women on the side of the road trying to change a tire, and the tire weighs as much as her. I always try to lend a hand with I can.