Degree is important here. America's trend growth rate is higher than Greece's. Its political system is less dysfunctional. Its economy is overwhelmingly on the books and taxed. Its labour markets are more flexible, its public sector is smaller, and its unions are less powerful. It's currency floats, and its monetary policy is its own.The bottom line is that it's not clear that there is any set of policies Greece can adopt which will prevent default. Debt costs are too high and growth is too slow. There are many different ways that America could close its budget gap; it's merely having an intense political debate over which way is the best way. This could potentially be a problem, but it's a different problem from the one in Greece.
We don't have to make spending and revenue perfectly equal. Nobody is saying we need to balance the budget in 2015. We can run deficits. We just can't run structural deficits that add to our debt faster than we grow the economy.