Looks like someone threw up a website but is waiting for it to get filled with data by general public submissions instead of taking some of their time to do research and start by filling in the facilities in the major cities. That information is easy to find between the government website and yelp both of which offer that information.
For instance the city of Seattle has a free shower program. When they realized that even small fees kept the homeless population from using the showers at the City Parks and Recreation centers they dropped the fees and made the showers free for everyone.
There are also "Urban Rest Stops" for the homeless in Seattle that provide free showers including free laundry essential toiletries of soap, shaving supplies, women's hygiene supplies, etc. The term "homeless" in Seattle does include people who are living on the streets in their vehicles. But of course if you can afford to make a donation then that would be important to do so.
The city of Seattle even has an interactive map showing where the public restrooms and showers are located.
