I've always felt uneasy somehow at handing over a tip. (Not that I grudge the money at all, it's usually well-deserved) It feels so patronising or condescending, (sort of Lady of the Manor "Thank you my man!")
We love to give a generous Christmas Box to our binmen, postman and window cleaner, but that's a Seasonal gift.
It would be far better in my view if service/hospitality industries paid good wages to start with, so that tips weren't badly needed by the poor workers.