I’ve got Ariats, but also some Lucchese boots, handmade in Texas. There are a number of others. But your point is right, they aren’t ubiquitous. You have to look for them and they are really expensive, which is sad.
Next time I’m in Temple I’m going to this custom bootmaker outside Austin - for the same price as top of the line major brand - he can make me a set. Ariats aren’t the most best boots but their sizing just really works for me. An 11 D is perfect but only an Ariat - my Justins are sloppy in 11 D