Whilst a horrible thing to do, anyone could panic and leave the scene of a crash. No one can judge until they are in the position themselves. Not an excuse for it, but who knows what you'd do in the heat of the moment. People that say 'oh I'd never do this, I'd never do that'. You don't know. You'd like to think you wouldn't. But you can never be 100% untill you experience it yourself.
This is the argument I'm using next time someone slates Hitler. You like to think that if you're ever in charge of a large european country you wouldn't use that power to condemn the followers of your least favourite religion to death camps but if you've never been in that sistuation you can't really judge.