Europe is a broad brush. Tap water is free (by law) in the UK, and there are only two places I've ever paid for a public toilet: a handful of stations cost 20-50p and a handful of nightclubs might have a bouncer who you appear to be expected to tip £1 in exchange for a spritz of cologne.

I'm not sure I'd say either of those chargeable toilet scenarios is well correlated to clean toilets, but I assume mostly they do that to try to avoid various kinds of mischief.