You can make a lot of money overseas, pay taxes to those countries, and then keep your money over there because you don't want to be double-taxed.
There is no "double" taxation. When the money is repatriated, you subtract the amount already paid in taxes on foreign soil from what you owe the United States. In other words, you pay the difference. Apple just has the sweetheart deal in Ireland where they basically pay nada, so they would have to pay close to the full rate to repatriate.