I dont have the answer to your questions, but if so Im not surprised they wouldn't say anything. We often tip well above when service is great and whenever we have tipped above at a tip included place they never say anything. I think it would be more awkward for someone to say, hey.....did you really wanna tip me that much?
We always check our bill too because we also had the same thing once at a restaurant elsewhere and our service was horrible. I just chalked it up to a lesson learned. I really hate when restauarants do this. On the flip side I can understand why they do, especially at a place like Disney where people are already spending so much. I could see where waiters get screwed a lot. I've just had to learn to open my mouth and complain if service isn't good at a place when I know they are going to take the tip out. And if service is great I still give them more.