no one has asked them to prove the 'undo strain' certain apps put on their network. all eBay needs to do is sue them asking them to prove that Skype puts undo strain on the network.--"WHEN THE LAUGH TRACK STARTS THEN THE FUN STARTS!"
Sue them on what grounds? There are no net neutrality requirements.
Anyone can sue anyone else. The question is weather or not eBay, Google etc. would have a cause of action.