Airports not listed for trade (White Giant)

When I go to "Products in stock; buy and sell" to look for things to purchase on the market, airports are not listed. They appear to be the only product missing. Even stuff like plutonium that isn't made on my planet and isn't currently available shows up with a buy link. Airports do show up on the "View world market; demand, supply and prices" list. Are countries specifically blocked from buying airports on the open market, or is this a bug?

They come free when u open an air transport corp

The only purpose of the air port is for an air transport corporation and to make additional relief flights, otherwise, they don't really do anything.

Yes I know, they serve the same function as production plants do for other corporations. Yet it is possible to buy and sell production plants, but not for airports. It looks strange.

You still need the production plant. Why worry about a mostly useless commodity?

Because I tried to build an air transport corp and waited several months while nothing happened, apparently because I couldn't get an airport for it. I had staff, and the other stuff it needed seemed to be appearing at a normal rate; the airport looked like the bottleneck.

An enterprise corp can be built that supplies airports. Currently there is shortage of 12 on LU.

Now 14, particularly fascinating since there's 100 airport corps.

Eh, it'll get there when it gets there.