They make trailers that are complete washrooms. Multiple sinks and toilets in stalls/single toilet and sink with running water. Also, they're heated. Septic truck comes every so often to completely service them.

Not just mass transit, we need to make cities walkable and pedestrian friendly. No more stroads. No more big box stores with ginormous parking lots. No more "outdoor" malls. It's just extremely inefficient use of land.