Most people see jumping from one building to another builder as... jumping from one building to another buidling. They don't really have a name for it because that's what it is. Skateboarding involves a skateboard so if you just looked at someone with a skateboard you would think they were a skater. It'd be hard to pick out a traceur in a crowd because it doesn't really involve anything other than your own body. It would be almost impossible to outlaw parkour, unless it were like "no running in the streets, or sidewalks, or using rails etc.."