Only because they dig such spectacular holes and everyone loads on so much of their debt. Check the incentives in my other reply to Tundur.

Sweden had to bailout their largest bank around 1996, bailout still not unravelled and they are already having problems again having had to set interest rates to zero to keep their housing Ponzi and such alive. Their reserve requirements are something  like 4 or 6% (better than UK where they are 0%).