In all my hospitality work, employers have justified low wages with reference to the tip the employees would receive. Accordingly, there's always been a lot of infighting between service and kitchen in the restaurant staff, also greed and gaming the cusormers by the waitors and waitresses, as well as customers using tip to exonerate themselves from shitty behaviour. I never accept tip precisely because of the harm it does to everybody involved. Obviously employers like tip as it seemingly reduces their wage obligations – even though a (legal) wage obligation is something entirely different from a tip (usually a sort of voluntary gift from the customer to which the employee isn't automatically eligible for). Tip is harmful, in my opinion, and people should refuse it wherever possible.