We have these in a new building I work in. There is a proper ventilation system. It’s a heat recovery system so cheaper than having an open window/ regular extraction fans and letting all that expensive heat escape.
There is a maintenance corridor that runs behind all the toilets so all the cisterns, flush mechanics and pipe work is accessible to maintenance which is much more cost effective. Less disruptive when one is being repaired as well.
It is obviously tricky if someone is taken ill in any loos. Possibly better to use accessible toilets which has emergency cord if feeling unwell. Same for people who are claustrophobic.
You can actually remove the toilet doors quite easily. Hinges are on the outside you remove the bottom cap from each hinge, slide out the hinge pins and unlock the door from the outside using maintenance keys. Lift out the door. There is always a janitor/ maintenance person on site when building is open.
This question came up before so I asked at work. It takes him less than a minute to get the door off. Maybe a couple of minutes to get there if at opposite end of building. It has happened a few times. Other people they’ve been with have raised the alarm. Often it’s small children who lock but then can’t unlock the door rather than someone being taken suddenly ill but there have been a couple of collapses.
I think this set up is only possible in new buildings though. It’d cost far too much to retrofit. I’m not sure what the answer is if someone goes in alone and collapses either. Possibly in years to come buildings will be be smarter with some sort of AI monitoring. Or our smart watches will alert someone that we are in need of assistance.