He owns a shop, is self employed. It’s him and another guy that does paint correction/ceramic coatingIf he’s not self employed, yes.
Some people don't like to tip and won't in this case either. Others will find a way to have an excuse not to tip. It's a very fine line since we can't possibly know the etiquette of everything. That's why the OP asked. I'm a better tipper than my wife, which doesn't make her a bad person, just cheap lol. But she will tip the person who hands her a pizza for pick up, which I do not. Go figure! I tip the guy who details my car because he's very professional and does a great job. In this case I would tip.Why not? If you are happy with the results. Makes no difference if they are the owners of the shop.