I believe your appearance is part of your identity. I'm not talking about gender identity.
Like I said, uniforms, shit the employer can make you wear whatever, but how you look, that's your choice, not an employer.
One great inequality I noticed when I was a front desk clerk was that the girls I worked with could look how ever they pleased. Huge piercings, crazy hair and what not, but the moment I walked in with a small ear ring, and a shaped up and trim beard, my boss freaked the fuck out and demanded that I change completely how I looked. I refused, and kept coming in, and every time she pointed it out, I'd point out the girls and herself, asking why it was okay she got to wear ear rings but I wasn't allowed to, and how a lot of the other guys had facial hair, but suddenly I wasn't allowed to.
I've dealt with employers being complete hypocrites telling me how I have to look, and I just don't stand for it.
I'm not talking about walking in looking like a lumberjack, but to say that someone with a trim and neat beard looks homeless is absolutely insulting.