Protocol to not tip. I tip my barber every time though. At Christmas I give them a $20. Figure they can really use the money.
I tip valet but avoid using it. I tip taxi drivers, food delivery. As a general rule I tend to avoid things that need a tip. Consumer choice, which it is why it is so annoying to get asked for one when one of the reasons I choose that place is because there shouldn’t be the added cost of a tip.