On the surface you might thing "this is obvious why do we need this"? Well not everyone actually knows how to act for one reason or the other. So it's always best to put thing up that explain how to do stuff. As for "please put toilet paper down the toilet" - in some African countries it's common to dispose of the toilet paper in a different location as you poop. I got no idea why but I know that it has been a problem in a building that an online friend cleans in.
This is just good to have around in public arias where people gather. We all forget from time to time or are in a hurry and skip the hand wash. So to remind us to do it is a good thing. Being that the building is mostly senior's it's a VERY good idea for everyone to keep clean and not cough on each other.