Of the five only Ireland made a huge unforced error in guaranteeing the banks’ bonds. The other four borrowed money on favourable terms they likely thought they’d be able to pay back given continued economic growth (as did Ireland). They were wrong about the continued economic growth but they weren’t the only ones. Plenty of German banks agreed with them; that’s why they lent them the money. Not being able to reform labour markets in Southern Europe isn’t the mark of idiots. If the voters won’t stand for something it isn’t happening no matter how brilliant the politicians they elect.