It's entirely pressure from other women. I've tried to wear makeup to work once or twice, but I find myself accidentally wiping it off on my shirt and smearing it everywhere. The cars I'm working on don't care how "made up" I am, but the other women who work front end in the dealership shit talk my looks from time to time. It doesn't bother me but I could see how sensitive/self conscious women can be bullied into wearing makeup to work.