That's actually part of the problem. The U.S. government has granted tax holidays in the past, where they radically cut the repatriation tax rate for a short period of time. On the one hand, that has encouraged companies to move money back into the U.S. from foreign subsidiaries, which can give the tax base a shot in the arm.

Unfortunately, much as people wait to buy from a department store until there's a sale, the fact that the U.S. government has cut repatriation taxes in the past means corporations wait until it happens again. Nobody wants to be the sucker who doesn't buy on sale.