>"What makes you think they can't? Or that some other private business can't provide the same service and do it better?"<
Because airlines make money putting peoples butts in thier seats. They advertize a morning flight to depart at 7:00am because business travelers wouldn't book an 8:00 am flight because it would put them in a time crunch. The airline knows that the runways will only handle 32 flights an hour but they will advertize, book, and fill 70 flights for that 7:00am departure that they know ain't leaving till 8:00am. What happens is you wind up spending an extra hour on the tarmack and don't get off till 8:am but they got your butt in thier seat. It's business.