Why shouldn't the female carer take a disabled boy into the male changing room, is it not better for the boys dignity?
I doubt many men would have a problem with that. I suspect she wouldn't want to, which is why it's wrong to frame "some 8yos tolerated in ladies' changing rooms" as a benefit to the male child. It's more a benefit to the female parent.
But at the point we've probably gone a hypothetical too far because the reverse doesn't work at all. The same women who would likely occasionally tolerate an 8yo lad in their changing room would quite rightly strongly object to an 8yo girl with her father.
I think some people in the thread have forgotten that the rules are clear. Once some one is past 7 they can't use the opposite changing rooms. What we're discussing is not changing the rules but whether in reality the enforcement gives a bit of leeway at the edges.
I think it does. I think if someone said to a parent "I'm sorry I don't feel comfortable with your 7.5yo child here." then the parent would likely respond "Ok, regardless of the rules, we'll leave it 10 minutes while you finish up". Equally if someone said "Is it OK if my 8.5yo changes in here." they might well get the response "OK, regardless of the rules I'm willing to tolerate that.".
That's not changing the rules, that's just people being decent and helping each other out.
Someone else made a really good point: It's not exactly a treat for the 8yo! My lad would be mortified if he had to change with Mum with the ladies. I'm sure 8yo girls would hate to change with men. It's very much a last resort for all concerned.