Of course they can. It's their aeroplane and their instructor. They can choose what services they offer to sell. The punter can then choose whether to buy them or not. Same as any other "club rules", like weather minima stricter than the law requires or currency requirements stricter than the law requires.
Or are you just happy to be walked over all the time?
Actually I have no objection to being asked to demonstrate a PFL once every two years! - of course if I'd done one the week before as part of another check ride I'd expect to be able to negotiate.