Square footage in prime locations is extremely valuable. One use of section of a street precludes another. Most land in America is privately owned. Way too much public space in cities has been devoted to roads, parking, and highways. So the precious little urban land available is fiercely contested. Should a section of a street be outdoor dining, greenery, parking, a bus lane, sidewalk, a utility box, product display, or a driveway? Who decides?

The law formalizes the boundaries between people. Without any restrictions people will consume as much land as possible until they come into conflict with others and use informal means to resolve disputes. Banning sleeping in your car or tents seems cruel until you experience the logical extreme of people settling permanently on public space. Stores would use the sidewalk as extensions of their sales floor and let pedestrians walk on the road.