often seen in the street without a hat

Everone has hair on their ass because, well yur ass is just an extension of your leg (or your back however you want to look at it) so unless by some freakish happy accident God (or whatever) has seen fit to give you hair on your legs and small of back but just magically miss out that area you will have hair there. It just depends on how dark and coarse your body hair is as to how noticeable it is.

Of course you could have waxed it off.