Wow - I went shopping with my daughter last weekend.
Store number 1: The women's change area was a row of four doors, facing directly out into the shop. The attendant holding the keys was male. He let you into one of the little rooms with a mirror and hung a coloured hanger on the outside to show how many items you had with you, while everyone else (male and female) waited outside. There was an identical men's change area on the other side of the store.
Store number 2: Same row of doors, only this time there was a divider wall between the doors and the store. The attendant was female. My daughter's door wouldn't close all the way, so my husband walked around the divider and gave it a good hard yank. We never thought twice about it, and the attendant didn't indicate that he'd done anything unusual..
Store number 3: Row of doors, dividing wall, AND a comfy place to sit!

This was definitely my favorite store. (Old Navy, actually.) The attendant was female, and the dressing room was co-ed. Both men and women were being let into the little rooms. Both men and women were standing around (sitting, actually!) and waiting for their partners to come out.
Oh, I forgot... there was a store No. 4, which was the same as the first store, except there were only two doors, leading into little rooms with mirrors.
I honestly don't see what the problem is with men waiting outside for their partners/wives/kids. I suppose it might be different if it was some kind of communal dressing room, like a change room at the pool, but I've never seen anything like that in a store in my town.