I have a young child, and that is an absolute free pass to nearly any bathroom anywhere. My kid is very cute and charismatic to boot, so I'm half certain I could make our way into Area 51 or the Vatican archives if we found ourselves with a full bladder.
I loved my time in Brussels but it really was gross how often I'd randomly smell piss.
I mean that's what I find hilarious about trying to do capitalism to toilets. People gonna poop and pee, there's literally nothing you can supply/demand about it. You can't do congestion pricing on a toilet, people will pee either way! You should just make it easy as possible to pee where you want them to pee, or they're gonna pee where you don't want them to pee.
I guess I shouldn't laugh, it exactly the same logic of trying to do capitalism around housing or feeding people...
The story on why it is free is quite interesting, as it used to not be this way in America either: https://psmag.com/economics/dont-pay-toilets-america-bathroo...
Many places are now putting codes on the restroom door that you have to ask for. Whether or not they'll give you the code before buying something varies a lot by location and likely by how much the employee gives a shit.