Some places just don't want their bathrooms put in an awful state by non-paying customers. We can respect that, but what about the emergencies?
We've all heard the horror stories, many of us have experienced it ourselves. Absolutly bursting, it's an emergency, no you can't just buy something after, no you can't just give me 5 bucks to use the bathroom. I know quite a few stories where people simply cannot control their bodies at some point in this exchange.
With all you very young/very old/very sick people in the world, it's amazing that people do not think of te emergency situation beforehand.
It's just stupid. By all means, say the bathroom is for paying customers only, but unless you want to clean up some messes make exceptions for emergencies AND allow employees to make exceptions for emergencies. At the very least- know where the nearest public bathroom is so you can say "paying customers only, but a public restroom is just over there"