They are required to follow ATC instructions and obey airspace restrictions. They do this willingly because it's really, really easy to get into a midair colli

They are required to follow ATC instructions and obey airspace restrictions. They do this willingly because it's really, really easy to get into a midair collision of you're flying near an airport. The only exceptions are for urgent reasons of national security, or when they're flying under military ATC.