I think it's very rare for the service charge included in the bill to go to the waiters. I don't even know if 'service' actual means the waiter service.

Best to ask the waiter if they get it or not. If they don't then leave a tip if you think they deserve it, for the amount you think they deserve. I hate the American culture of always tipping. A normal tip should reward normal service, with a bigger tip rewarding service above your expectations. But if the service is poor (as it so often is here) then they haven't earnt a tip in my opinion.