I think only one maybe two of ARS racks have the window and I know the cb-70 racks do not have it. The racks with windows are for larger snake or maybe a massive female ball.
ARS (which the OP wants to purchase or has) and Freedom Breeder racks are free hanging and light comes in from every side. I feel the benefit of the animal's privacy far outweighs the benefit the keeper may gain from constantly viewing his animals. I will admit not all balls are shy but if you have a rack of 30 I bet a few are.