I haven't seen coin-operated TVs ever, but I have vague memories from few decades ago that some hotel TVs did feature some pay channels, one or more obviously offering adult entertainment content. However, I can't remember how the usage and payment worked, might been something like that if you switch to those pay channels then the TV set or set-top box hooked to it noticed that and after watching for more than short grace period, this information was recorded into the hotel billing system.