The rivets along the bottom are what rivet the painted body to the tubular chassis. If they were painted you would have to mount the body unpainted and rivet it then paint it which would make paining the inside impossible or you would paint rhe thing twice. As it's usually water based this too would be difficult as you would be putting water based paint on top of lacquer. The rear reviews are painted because they are there along with the wooden frame when the tub is painted.
