It's actually an insidious population control tactic.
You ever hear car owners talk about how tethered they feel to their cars? They always have to look out for their car and keep it around.
That's like having a giant ID card that you can't leave anywhere. Perfect for tracking citizens.
Also, it helps with tracking lower class people who are more likely to be criminals. Since poor people can't afford cars, and mugging people requires being on foot, a walking man is an instant target of suspicion.
It's quite brilliant.