Private companies often come running to the government to protect themselves from competition. Sometimes they are successful, and get government licensing and certification requirements that help create barriers to entry that protect incumbents (if incumbents are lucky, they will actually get to control the licensing and certification board and testing process).
But whether or note private companies have the political muscle to get this kind of protection, the government almost always protects itself whenever it embarks on any sort of quasi-commercial enterprise. The ban on first class mail delivery competition is one example (as an aside, when email began making an end run around this ban, the USPS actually made a [fortunately failed] play to be the monopoly email provider). In Denver, there was a story a while back that after they built a new toll road, they added traffic lights and lowered the speed limit on a parallel free road to drive more people to the toll road.
"When the old arena for the Orlando Magic opened 21 years ago, it was common for Parramore neighborhood residents who lived nearby to charge Magic fans and concert-goers to park on their property. But five weeks ago, the Orlando City Council approved standards that will likely keep most Parramore homeowners from profiting on parking near the Orlando Magic's new $480 million Amway Center (pictured above).
Among other things, property owners must pay a $275 application fee and provide a business tax receipt. Lots must have an attendant, signs, proper lighting and a paved, gravel or grass surface free of potholes or ruts. City officials also recommend hiring security. Even when all those requirements are met, temporary parking lots are allowed only during an event expected to draw at least 5,000 attendees. So far, five applications have been approved, but all are for large properties such as churches, not homeowners.
The city, meanwhile, has doubled its event-parking rate to $20 at the two garages closest to the Amway Center; elsewhere, event parking at city garages and lots is $10."
The last sentence explains the first two. They are trying to charge an above market price for parking, so must constrain supply to avoid being undercut.