Oh you haven't heard two flushes followed by the sound of someone dipping their hands into the bowl, followed by splashing and rubbing. And then a manager walks out and makes suspicious hand movements towards you before you skedaddle
I think you missed the "seconds later" part. Even if they run water after flushing, they haven't done it more than a second or 2, and thus have barely gotten their hands wet. They haven't even come close to cleaning anything.