Obviously the ginger thing isn't the same as racism, but hair discrimination has its roots in racism.
It's usually schools, companies and other organisations who have a dress code that includes hair, but it's based entirely on the type of hair white people have. So black hairstyles end up being classes as 'unprofessional' or against the rules, and then have to go through various time-consuming processes to make their hair acceptable.
I heard of one in Japan where a student had naturally brown hair, and was forced to dye it because the rule is 'black hair only.' What the rule should have been, if they have to have one, was no dye, but the people coming up with the rules couldn't imagine that anyone would have a natural hair colour other than black. It's not even malicious racism, it's just the sort of thoughtless racism where you clearly don't have any minorities involved in these decision-making processes.