Originally Posted by Policy Wonk
You don't have a clue what your talking about,
He's part right.
Airlines pay for most airport projects at least indirectly. However, the whole system relies heavily on public financing, public interest rates, and public ability to push projects forward, use imminent domain, etc.
Left to their own means, the airlines would have very little financial or political ability to build anything, and the industry would be severely hampered by it.
Further, airlines rely heavily on the ability to grow/shrink without the burden of having to spend several years building first, and without debt load for facilities they don't need anymore. The whole model needs someone to provide "central services", whether that's a company or a government.