Facilities will vary greatly depending on where you are at. From my experience, they are certainly not as frequently found and/or accessible as we are accustomed to in the USA. Here in the states, in most populated areas, we have a multitude of fast food restaurants, gas stations, etc. where you can often walk into and use a restroom without any obligation to purchase something. That's not the case in much of Europe. Bathrooms are often hidden in the back of an establishment and it is pretty much expected that you will purchase something (a drink, coffee, etc.) before you ask to use them. Likewise it is not uncommon to find that you must also pay to use the facility. Permanent restroom kiosks/booths are common in cities and you pay a fee to get inside the door. I've seen some very ingenious bathrooms over there that may take you a minute or two to figure out (how to get in, how to get the auto-seat-cleaner to work, how to flush, etc.). I have found that the restrooms in most restaurants/bars are very small, but usually fairly clean. In tourist areas, restrooms are viewed as a moneymaker by the owner, so there might even be a person to collect your coins as you enter.
Just a few of my potty thoughts. Next time I'll share how I locked myself in a bathroom in Rome a few years back. I had to call for help. :-)