Shoe factories, as far as I know, never make their own shoe trees. All are re-branded stuff and rarely worth the markup prices. G&Gs are an exception because their shoe lasts have such strong shapes that readymade trees can never support them like the orinals.
...just to stick my ladle in this soup: Daisuke Yamashita, the bespoke savant who has travelled the world over several times just to meet makers, has chosen Maftei as "the best" value-for-money shoemaker. Just one opinion, of course, but a very learned one.
I actually have an old interview with Daisuke-san, it can be found from my little site's archives. It was fun to interview an interviewer and, yes, he has been all around the world just to meet artisans. Japan seems to have many extremely devoted connoisseurs in any field.