Nature is nature and we often cannot control when nature calls. In this time period most public spaces have some type of public restroom facility. Where I live in New Hampshire, like a lot of small NE towns, the only activity is walking up and down the main street and seeing the different sites and people spend hours just seeing the town, but there is nowhere to use the bathroom. In the United States, often, one might see a bright blue or green port-a-potty, but they are so gross, often unmaintained and smell worse then a sewer, they become more of a deterrent then an attraction.
Traveling throughout Europe for some reason I have always found nice public toilets set up around the city. None of them have ever smelled that much better then a port-a-potty, but they provide a huge service to the way space is occupied around the city. If there were two parks and only one of them had a bathroom I would always choose the park with a bathroom over no bathroom. But the importance of bathrooms, in the modern era, is their efficiency. Port-a-pottys are not efficient, however most of the public bathroom in Europe are clean, stainless steal and work quickly and in a small amount of space. In both Paris and Vienna, for instance, both public bathrooms flush, have an automatic soap dispenser and automatic water switch, like modern bathrooms in restaurants. The bathrooms don’t scare people away, but give them a good option, so maybe they stay out longer or decided to go to a certain park and meet with their friends.