I find it hard to believe AWS would try to suck blood from a stone. I’m willing to believe they get a 55k bill, but do they actually end up paying those?
I think you can get refunded for fraudulent charges, like if you get hacked. But if you leave an instance running or screw up auto-scaling somehow, that's normally when the charges may tend to stick around. I believe they have a one strike policy, though that could have changed.