In 1953, Canvey Island was largely open land, with a few houses built mainly by Dutch settlers (they have a bit of form for making low-lying land usable
Londoners would use the land for weekend camping/ holidays. It was public land, nobody owned it. (see where I'm going with this?) After the floods, people began arriving with stakes and fencing and "staking a claim"........only to find ,on their next visit, their fence had been subsumed by a larger claim.
It all rather sounded like the Klondike, during the Gold-rush.
Ultimately, order was restored and local councils raised rates-revenue from the squatters. more roads attracted more houses attracted more rates.
So, public airspace is sequestered by parties who have a vested interest in erecting invisible barriers around "their" staked-out claim. Subject to their rules and conditions, they'll let you in and out of the bits that they aren't using (I concede that it's a good idea to restrict access to the approach and departure "lanes)
If you agree to pay to use what you already "own" It's a small step to start charging for the air the occupants and engines breathe..... Well, it's a carbon tax, innit....just like the iniquitous London Congestion charge)..... serves them right! boycott the place. *smug*
As regards the sale of the 49% Public ownership,- given the total failure of privatisation, to return anything to the taxpayer, why would you sell a revenue-stream in near perpetuity, for a one-off payment, which will be frittered for short term gain or a HS2- like Vanity- project.