They probably think what they're doing is art. I dare say they wander round beforehand trying to get into character or some such bollocks, but all they do is stand still and hope people look at them. Well I don't like them. Can you imagine meeting one at a party?
Worthwhile human: "What do you do?"
Worthless entity: "I stand very still. The other day I stood very still for 4 hours. The stories I could tell you about standing still...Where are you going?! Come back!!!"
They're sad attention seeking people with no skills.
Ignore them!