Reading all this makes me just love my cultural environment so much more. Service and all taxes statutory included in price and tipping is truly voluntary and not automatically expected. On the other hand I'm in trouble in other parts of the world.
But staying in subject, have been asked even here sometimes by brothers and sisters why I'm tipping (because the food was great or service outstanding!), they claim they would not do it even in their wildest dreams. However these are minority, thankfully. In overall I think it would be kind to make pre-booking for groups of over 6-7 persons.
CP