Companies are only profitable because they serve their users better than their competitors.

You cannot seriously believe this. Is a parking company only successful due to how well it serves its users? No, it extracts rent.

If the parking compny pays rent to the parking space owner (based on the auction’s highest price), then yes (the owner gets all the rental profits).

I have seen multiple times cases where an establishment has parking spaces outside that are not paying to that establishment. The customer is basically tricked into parking on spots that seem to be free for customers, but is in fact not: those are further away. The only reason it seems is that this gives more fines, and more profit to the parking company. Neither customer nor the establishment benefit from this at all.

Is the parking company the only option? If not, then yes, it's serving it's customers better than competitors.

The proof is the fact that if they charged $100 per hour, they'd have no customers.

Maybe replying with "companies" was too broad, but within the context of airlines its correct

People paying to park there are getting something they value.

Only true in markets and industries where there is a low barrier to entry.

Or because there are no competitors. Allocating parking slots based only on bidding has the potential for one company to become a monopoly by purchasing all the slots, allowing them to charge ridiculous prices while providing bad service.