But you can't tell who's a Muslim or lesbian just by looking at them (usually!). So not the same.
You often can, but I agree its not quite the same, but a close enough parallel to make my point, its racist and encouraging sexual harrassment
But I agree that it's unpleasant, Ginger is not 'red' or 'strawberry blonde', it is what it is and a lot of children and young people are bullied if they have it.
I think ginger/red are more or less interchangeable and includes strawberry blonde, the latter being a polite description of light ginger. Young people do get teased (bullied) a lot, in much the way people with glasses were once teased (bullied) , one symptom is the deliberate mispronunciation of the word with a hard 'g' and to rhyme with ringer.