Considering women who don't wear makeup to be unprofessional is, in my experience, a culture thing. I'm from the west coast of the US, and I don't wear makeup. It's perfectly acceptable out here, as long as you are well-groomed, to go au natural at work.
I spent a few years living in a southern city, where the culture is quite different. I had trouble finding work---getting past a first interview. I finally figured out it was because I didn't wear makeup. So I started wearing small but visible amounts of eye makeup and lip gloss, and got hired in an office environment immediately.
One day I wasn't feeling like wearing the makeup, so I just put on lip gloss and left my eyes bare. I was actually reprimanded
by a superior, because it was 'so unprofessional'. It was absolutely shocking to me, to the point where I threatened to file a complaint with HR, and the superior honestly couldn't understand why I was threatening her. She kept repeating 'but it's so unprofessional.' Finally I blurted out "Not where I come from!' And we both froze for a moment. Then we had a really good dialogue, where she explained to me how normal and expected this was there, and I explained to her that out west that kind of expectation would be considered rude and intrusive.
I wore makeup for the rest of the time I was working there, which wasn't very long. I headed back out west as soon as I could.