Most austerity program fail because there is no true austerity. Outside of Greece which has had to make real cuts simply because it hasn't the money the vast majority of countries which claimed some form of austerity never actually cut spending, some kept increasing it.

In the US it is all a shell game where the deceit of baseline budgeting allows Congress and the President to claim cuts when spending increases. The US could balance its budget in a manner of years if budgeting were honest and they actually reduce spending increases below inflation.