"Air Transport" Corporations (Little Upsilon)

I was just wondering if anyone knew whether or not the inability for Enterprises to build "Air Transport" corporations is a glitch in the game, or if it's supposed to be like that. I noticed because I kind of accidentally acquired one of these corporations by purchasing shares and becoming the principal shareholder, and I noticed it'd be profitable to build more of them, but when I went to do so I noticed the option isn't there, however it is when I go to build a state corporation. If this isn't simply a glitch, are there other corporations that can only be build by countries? or corps that can only be build by enterprises?

You need an airport to build air transport corps. Since you can't phyically own an airport in a country with your CEO then you cant build air transport corps. Its not a glitch. I think you can build every other corp with a CEO except AT.

Everything but air transport, because you can't build the airport, but you can buy the corp.

Still can't move it though because it needs the airport.