I find it odd that people think it's acceptable for disabled people to have to share with parents who need to change nappies and not dysphoric people. I mean, many larger places have family facilities anyways these days, but I don't understand why disabled people should wait for people who need to change a nappy, but waiting for a dysphoric person is going to destroy everything disabled activists have fought for. Why should being a parent give you any more right to be in disabled spaces? It's well known that parents didn't decide that that was a great arrangement, but the idea that bad arrangement is okay but dysphoric people are a step too far is ridiculous.
I've said it before and I'll say it again - people have been fighting for other single stall unisex facilities for literally decades for many reasons and for many reasons people in power say this can't be done. There is no space, no money, not enough of a need, that if we have such body issues we won't want to swim or whatever anyways, and so on. We've been told to use the disabled facilities for years often because 'if it's so bad you can't use your own sex's facilities, it's a disability'. We can come up with all the possible solutions but if people in power don't give a fuck, it doesn't get done.
Much like the often called 'honour system' of trans people using the other sex's facilities, this has been going on for some time. Yes, some people abuse it. Yes, we need better solutions which people have been fighting for - extra single-stall facilities, proper attendants - but those solutions aren't in now and those who have been fighting for solutions are far too often ignored by both sides. It shouldn't be a free for all, that really isn't a good solution for many reasons, but it also shouldn't be constantly out that we're all some sort of bogeyman who just leech off of everyone else when no matter what we argue, we're told it isn't enough for anything but the laziest changes by those in charge. I'm a dysphoric disabled parent, I would love better facilities, I've been arguing for them for years, but until that's a reality, we have bad arrangements and hodgepodge solutions that don't make anyone happy. The only local council pool left where I am is inaccessible to me anyways for entirely different reasons as their solutions are shite but I'm not going to blame anyone else other than those in charge for the ways things are now.
And yeah, radar keys are sold on eBay. They are also sold by Age UK, Boots, several disability charities, and many other places because not all disabled people get PIP even when we try, many people don't want to go through the process again after previous draining painful experiences with the system designed to deny us, and many who do get them with PIP lose them and it's easier to buy them online. That has also been going on for years. If you haven't noticed people abusing the radar key system in the last decade or so that that's been a thing to the point you're surprised by it now, I think there isn't enough of an issue to try to fight against access to accessible toilets but more arguing there should be more of them.