when governments become effectively insolvent they default on the debt
U.S is in worst shape than Greece! Nouriel Roubini Discusses U.S.. Government Deficits
Roubini : if you are a private sector company you live and work in a market and unless you become more efficient you do not survive and disappear , while in the case of governments that never happens , when governments become effectively insolvent they default on the debt , and that's what's may be happening soon in Greece and in the rest of the Eurozone , eventually that may also happen in other advanced economies ...so there is not really a market or competition for forcing the governments to make tough choices ...