There are definitely laws that deal with this issue. In California for instance, "restaurants" of a certain footage must make their bathrooms available to customers. Most likely free of charge. http://www.ada-pros.com/know-before-you-go-restroom-requirem...

Chicago definitely has a bathroom problem though. See, e.g. http://articles.chicagotribune.com/2013-08-21/opinion/ct-per...