I was just in Paris and I never had to pay for the public sidewalk toilets. Where did you see paid ones? I didn't get to all the arrondisements, so I'm curious.

I don't remember actually. I was staying in Montparnasse so the 14th. Was 1 Euro wherever it was. Might've been this one: https://maps.app.goo.gl/5vPoD7jM3ELyP6gL7

And it's not this other one on the same street, cause this was free https://maps.app.goo.gl/Firjcsabthu8DHtQ6

That makes sense; I didn't spend any time in the 14th. I did notice a big difference in public bathroom availability based on arrondisement, but all the ones I saw/used were free. (The ones that weren't closed or out of order, that is...)