Why are we required to tip hair dressers?

I understand the concept of tipping those who offer a service (waitress, bellhop, valet) but that's because that is the sole way they bring in an income. The money I pay my hair dresser goes into her pocket as it is, and then on top of that I am expected to tip her, and buy product that she profits off of as well. Seeing how she works in a high class salon, it already cost me $200 for color, cut, and style, and then I'm expected to tip 20% and even more so during the holidays. I do it for the sake of not getting my hair butchered but WHY?





If it's expected for hairdressers to get tipped more during holidays, does everyone tip a waitress more during the holiday season?Why are we required to tip hair dressers?
If she works off commission only then yes it goes into her pocket.. but if she buys all her products like color, bleach ect then it goes for the cost of her products that she uses on you. If she works off commission and has to pay booth rental then the cost of her prices go up to compensate for her booth rental and supplies. If she works in a salon that is owned and she gets paid a salary and the money goes to the owner then her tips go to her. Tipping is a generous offer. she spends time to do YOUR hair the way YOU want it. I think if you can afford a 200 dollar color service you can afford a 40 dollar tip. You don't have to buy the products she sells and if it's such a big deal then find a cheaper stylist.Why are we required to tip hair dressers?
Understanding the concept - what a marvelous idea