I am glad this thread got bumped up. We had been told by some people, they had rest rooms on some buses,although I could not imagine how that could be really, since, every seat is a valuable piece of real estate. ..this was not the case for us. With no stops along the way to the inner cities on ships itineraries, you better have no emergancy!
We found in Florence, after our walk into the square, there was a tourism office that had rest rooms, and that was the only one that had a charge...it was .60 euros Every rest room we used in other ports was free, and many times once the bus arrived at our destination, there was a rest room, very close. Eating in a cafe they allow their patrons to use their facilities of course.
The only time I heard of a hole in the ground, was in Rome by the Collesium.
Many times there was no top seat, just the porcelain,and the flushes were on the wall..One sink had a pedal on the floor to push to wash your hands.
Most of what he heard from people in the know, was the worst of the restrooms are in small villages all over Europe. Thankfully we didn'r see the worst.