If somebody says they don't mind if you pay them below minimum wage, it doesn't mean that it is legal. At some point in the future a lot of hurt might end up coming your way, and you could be forced to pay them the remainder, even if they say they don't want it because they might lose their job as a result.
Similarly, just because Ireland told Apple that they could get low taxes, doesn't mean that they were legally entitled to do so.
Similarly, just because Ireland told Apple that they could get low taxes, doesn't mean that they were legally entitled to do so.