It does show a few of them, but it also shows an apartment complex miscategorized as one, and misses several within the city centre. They are shown with various names ("Toilet", "Public toilet", "Public toilet for men", "Public restroom") so I think this is crowdsourced, rather than anything Google has made an effort to map.
Although the interface of https://www.openstreetmap.org/ doesn't have a way to highlight them, other interfaces (phone apps etc) can, and OSM has much better coverage.
Everybody drinks water. It often isn't intuitively obvious where you can find water. Even in city parks, water fountains may not be where you expect but often are where you wouldn't. Google maps also sucks at finding bathrooms. Everybody pisses, even cyborgs.
Is it reasonable though?
Should Google Maps show me every single public bench too in case I need to sit down?
How about if I'm an avid cyclist, should they also show me every single secure railing I can lock my bike against?
It’s almost like this isn’t a thing folks are actually looking for.