This is merely an issue of not enough power available from certain ports, not a Mac vs. PC thing. You'll notice one of the ports they tested was on a Mac keyboa

This is merely an issue of not enough power available from certain ports, not a Mac vs. PC thing. You'll notice one of the ports they tested was on a Mac keyboard. The keyboard is self-powered and has a built-in USB hub for the mouse. Those ports have less current available because the keyboard, mouse, and hub consume power in addition to whatever the iPad uses. The host machine has to supply power to all of those. This is why some USB hubs have a power injection connector. It allows them to supply the same current to downstream devices as the host PC.