Leaving The Engine Idling

One more habit that i have seen, but this one i have no clue about the reasoning for, is when parking the car on a slope in the person's drive, rather than the usual practice of using the handbrake, using a bag of sand behind the rear wheels. The car i notice in my neighbourhood with which this is done is a brand new Vios, so i can't imagine the owner thinks the handbrake cable is going to snap. It's only a slight incline anyway. Anyone else seen this before?

Maybe he likes drifting and is afraid the parking brake will imprint on the red-hot disks. I personally use a concrete block instead of a sandbag, but that's because there's no room to fit a parking brake after jamming an RB-20 in my old crown.

EDIT: And of course, he must be a master drifter to be getting sideways in his FF Vios.