I assume that the signs are either:
a) a joke commenting on the ridiculousness of sorting waste
b) part of a research study
Both of which, based on my experience, are highly likely in Germany.
Let’s assume for a moment they’re neither.
Instead, let’s assume – there’s some ongoing business value to signage – what might it be?
Perhaps there’s some nuanced difference in how the urinals are cleaned.
Perhaps it’s a way to manage drink sales.
Perhaps this is a clever way to get the mens’ room line to move at a frequency closer to the womens’ room line.