No, I don't mean curbing propriety. I mean curbs that are owned by companies. Right now, public buses have bus stops, typically with a shelter of some sort against wind and rain. Everybody who lines up there gets on the public bus. No hard feelings if another bus comes right behind them.
What if buses were privately run? A common public bus stop like this wouldn't work. All the passengers would get on the first bus to arrive. That would give the bus companies an incentive to race from one bus stop to another to get all the passengers. That would be dangerous for all concerned.
A solution to that is to sell a bus company the right to pick up passengers along a stretch of curb. Easy to enforce, and then you have sanity among bus drivers, and less stress and safety concerns to boot.