Lets begin by saying that I completely agree with the argument that "if that's what the regulations are, then shut up and put up, or find another job". The company doesn't HAVE to hire you. They're not obliged. If they decide to impose regulations on your appearance, then either meet those, or don't work there. Your choice.
I've worked places where I've had to remove my piercings, but it's never bothered me. It's part of the job. In the same way that, if I'm required to wear black trousers and shoes at that workplace, then I wouldn't dream of turning up in jeans and white trainers, for example.
However, I do think such regulations are more appropriate in some places than in others. Do I care about the appearance of a ride host? As long as their uniform is presentable, they're clean and they're not wearing anything obviously dangerous, then, no, I don't. As others have pointed out, other situations (eg food outlets) are a different situation. It's all about finding what's appropriate for your line of business.
In this specific case, the 'issue' is "dreadlocks". Now, if we're talking about corn-rows/braids, that kinda thing, then I don't really see what the problem is. I don't associate them with being untidy, unclean or unpresentable. However, if we're talking proper back-combed, unwashed, crusty juggler dreadlocks, then I don't think I'd be too impressed at seeing those in a food outlet. Hmmm, dunno.
My current job has probably the least prescriptive dress-code of any I've ever had, which may surprise some considering I work for a County Council. Generally, people are grown up enough to manage to dress appropriately on the days they need to (important meetings etc), but if they're just sat at their desk in the office, does it matter if they rock up in jeans and a t-shirt? Apart from the exhibitionist twat in our office that insists on wearing a kilt to work purely because he knows it'll get him the attention he seeming needs to survive, people are usually pretty sensible about it. There's also one girl who's got purple hair, tattoos everywhere and more piercings than Taylor's had hot dinners. She scrubs up well on the rare occasion that its required of her, so what does it matter?