It's just cultural in Asia, here in Hong Kong the same 10% service charge exists at 99% of restaurants as well as hotels, many of the 1% that don't charge it make a big deal about that. As a cultural equivalence, I feel the same as you when I go to the US and "have" to pay a 20-25% service surcharge that isn't even disclosed on a restaurant bill . At least the cheaper properties have a naturally lower charge since it is percentage based so you will pay for better service, and it is (normally) fully disclosed.

You have made me aware that the Taiwanese properties are "misbehaving" (in my view) on encouraging bookings via their website directly and removing Marriott benefits, so that is useful knowledge, thanks.