AIBU to expect parents to supervise young DC in public toilets?

[WarmthAndDepth]

I hardly ever venture onto AIBU, but this one really gets me After a few weeks of using lots of public toilets at campsites, festivals, theme parks and various civic events, I am so tired of finding these facilities dirty, unflushed, blocked etc, and 4-year olds skipping out of cubicles unsupervised, having weed all over the seat and trailed loo roll across the floor. AIBU to expect kids to be supervised when using the loos in places like these to ensure they stay fresh for others? Especially loos which are unusual, such as chemical portaloos or festival composting toilets with sawdust, where the routine is different. I go in with / after my DC (both under 10) just to make sure they use it properly and don't leave a mess, but I have been shocked this summer to see how many quite young kids are allowed to use toilets unsupervised.
At the school where I work, teaching staff regularly do a quick clean up of the toilets mid-morning and after lunch as if we waited until the cleaner arrived at the end of the day, the loos would be unusable. Obviously parents can't supervise DC in school, but I feel like I know that a great many primary aged children are not able to use shared toilet facilities appropriately, and that, when out and about, young children are best supervised in public loos. AIBU?

4 year old fair enough should be watched.

You said under 10 though do you really think a 9 year old doesn't deserve privacy?

Privacy, yes. I still accompany my DC1(9) to the 'facilities' when we're out somewhere and although I don't go in with them, I'm there and pop my head in afterwards to check it's fresh for the next user. Today, at a water park, DC1 (who would never do this at home) had left the seat wet (from sitting down with a wet body), not flushed and put a blue paper towel down the loo. Fixed it. Last weekend, in the kids' area of a festival in which children are expected to be supervised, the compost loos were wild; puddles all over the floor, poo on seats, saw dust all over the place. Dreading the chemical loos at our otherwise gorgeous favourite campsite next week, where children are left to their own devices by otherwise responsible parents, regularly leaving the toilets unusable. Urgh. And I am not particularly squeamish or unduly worried about cleanliness.