It’s not that Hamburg doesn’t have public toilets, but Hamburg is known for the “Reeperbahn” - a street lined with bars (I think the American equivalent to it would be something like Bourbon Street in New Orleans?). People go there to get wasted off their asses and no matter how many public restrooms you put up there, they will piss wherever.

(There’s also an amazing documentary series about the Supermarket on that street and the characters that visit it)