Does the Legion AI never built planes?

I have played as the NCR about 5-6 times now, and no matter how hard I try to stack the odds against me, the legion is always pretty easy to beat, and I think it has to do with the legion never building planes.

In all of my runs I have almost full intelligence on the legion, so I exactly know what they are working on, and I have never seen them even making one plane, the only nation in the legion faction building planes are the navajo. I just wonder, is this normal? Is there any way to make the ai build planes?

When I once also switched over to the legion mid-war, I saw that they had researched a good part of the plane research trees, but they specifically never assign any factories to building them.