That's been our experience, too. Never seen staff 'hovering' on any of our 16 cruises/crossings, including our most recent one on QV in June. Indeed, like Victoria2 we have not infrequently had to actively seek out waiters/sommeliers in order to discreetly give them an envelope. We don't tip on every voyage, but have never noticed any adverse reaction if we don't. Nor, thankfully, have we ever received any obsequious gratitude if we do tip.