That's not it at all.
The owner still sets the uniform even while they have to make small exceptions. The owner still tells the Pentecost employee what length, color, material and general appearance the skirt has to meet, just as they do for the Hajib today. Based on my experience ordering my own pants for fast-food in highschool, the employer can even require that you order from a certain catalog at your own expense (you wouldn't believe the quantity of alternative approved uniform pieces KFC has). A Muslim KFC employee had the right to wear the Hajib, but it has to be a solid color with no writing, of either red, blue or white, couldn't cover the face, had to be tucked into the collar, and couldn't otherwise dangle or get in the way.
Just because a pregnant employee has the right to un-tuck the uniform shirt, doesn't mean the employer lost the ability to set the uniform. An amputee can pin up the pant leg, doesn't mean the employer can't still require uniform pants. An employee on oxygen and has to have a tank doesn't mean the employer can't prohibit writing or flair on the tank or it's carrier.
We say "small exception to the rule", and you respond with "complete and total loss of control". You're being hysterical. The only thing the employer needs to give on is allowing a skirt. Everything else stays well within the employer's control.