Back when I was living in a apartment / cave, I wanted to use these things so bad. I would have needed a stack of like 20 of them every time I left though, because college kids just don’t care about things like “parking lines” or “dogs”, they just park on top of them both.
When I was in college I’d leave notes on cars in the parking lot with lights left on “you left your lights on, you asshole” so they knew when they came out why their car wouldn’t start. In retrospect, perhaps the “you asshole” wasn’t such a nice idea.