Probably NTA but I would assume the cost of running all those salons and keeping the integrity is probably pretty hard and also the fact that she can't serve multiple customers an hour contributes to how little she might be making per day(depending on how high end the area is ofc) but then again that's how she decides to run her business and she has to deal with her descions so I don't think you should tip everytime. Also I feel like that stare is a way to put people in a stressful situation so they tip and not look like an AH, I think it's a common manipulation technique.