why would they think they could get away with it? -
Its the same mentality that says "I can drink and drive anytime I like, because I am a safe driver". In other words, it wouldn't matter what the odds are, they are sure they won't be caught or have to pay the price, because..... The will make up what ever excuse or reason it takes.

I like the way Ford Prefect put it, when confronted with the choice of eating some berries left by the cavemen.

"Look at it this way," Ford Prefect had said, "fruit and berries on strange planets either make you live or make you die. Therefore the point at which to start toying with them is when you're going to die if you don't. That way you stay ahead. The secret of healthy hitch-hiking is to eat junk food."

To which eventually Aruthur comes up with :

"It's there for us to eat. Either it's good or it's bad, either they want to feed us or to poison us. If it's poisonous and we don't eat it they'll just attack us some other way. If we don't eat, we lose out either way."

So most of these folks use similar kinds of logic to meet their expectations.