So then the city has to issue parking passes plus guest passes, and then actually enforce them. Seems totally impractical for all but the densest cities.
Sure there's some administration but it can be mostly handled digitally nowadays. I've seen it work in many cities that are not particularly dense by European standards.
The enforcement are handled by the same people that do normal parking enforcement. They scan the plates, see if there's a valid permit/ticket and write a ticket otherwise.
Which "people" do normal parking enforcement? Most cities do zero parking enforcement in residential neighborhoods unless someone specifically complains.
