That's true, though it's a tricky problem. The requirement to fly was to ensure airlines weren't buying gates, then not using them, solely to stave off competi

That's true, though it's a tricky problem. The requirement to fly was to ensure airlines weren't buying gates, then not using them, solely to stave off competitors. That situation results in less capacity, direct-connect cities, flights, etc, to serve the airport's customers. It's also not feasible to switch carriers too often, as the carriers need some amount of infrastructure of their own, time to fold in service/schedules, local employees or contractors, etc. Some airports now have common use gate terminals, networks, kiosks...that helps, but it's only a small percentage of them. I'm sure there's a better system for how things are now, but I think it was set up with the right ideas in mind at the time.