I've lived in Pittsburgh a clear decade now and the phenomenon of parking chairs is one of the most charming local oddities. Here's a video from Dean Bog about the parking chairs.
Yinz can't park here.
Parking in The Strip shortly after moving to town, I gently shunted a parking chair to make space only for local pedestrians and stallkeepers to crowd around and yell at me like I'd run over a puppy. I backed out of the spot and a man carefully moved the chair back into position, glaring at me all the while.