I have never had a job where make up was mentioned except to say that IF we wear make up it must be light/natural looking and if it is too obvious we will be asked to remove it or sent home. Almost every job I have had with a dress code has specified natural/light make up if we wear any. Only restrictions, no demands. Currently I am not allowed to wear finger nail polish although I occasionally get away with clear. (I work in a butcher shop by the way). i have never experienced any sort of bias. I however do have pretty good skin even though I am pushing 40. partly because i have never worn much make up

and never tanned. I do wear moisturizer....thats the difference between looking 25 and looking like the crypt keeper. For a while I worked for tips and did get better tips when I did my hair and wore a little mascara and foundation. It was not required but hey, whatever filled the tip jar.
And I think basic grooming and looking professional goes both ways. I used to work at a job where women could wear nice knit t shirts but men had to wear dress shirts and ties. Also, when I friend of mine complains he can't get a job I want to scream at him to shave his stupid beard because no one will hire him with that thing on his face. I think he would rather starve. I knew a guy who owned and ran a high end retail specialty store and always had clownish facial hair. So unprofessional. People did not take him seriously as a business man. I think men shaving is far more important and required than women wearing make up. My friend had a job once and if they showed up with so much as a five oclock shadow they were handed a razor and sent to shave before they punched in. seriously. I am sure the women were expected to wear make up there. a certain look was expected.