Is it USB 3.0?

I know USB 2.0 standards are 500ma per port but USB 3.0 can go up to all the way up to 5A
Seeing that it is a Mac I bet they make each port at least 2.1 Amp to be able to charge the iPad on it.

Edit: A lot of USB 2.0 ports have high Amps to enable you to charge your phone etc... Often it is 1 dedicated port on your laptop that will have a lightning bolt on top of it.