That's the main problem by far in my opinion, like prophetiko said, there is always a very slight chance of any auto beans failing to Autoflowers, but Id say for the well known, reputable companies, they may have 1 in 200. They do take the years that is required to cross a ruderalis to a sativa or indica and work it to a full auto strain.
These smaller guys fail to do that in many cases. Take the do-si- dos autos I have going now from puff puff pass cultivars. Its looking like im only gonna have 1 out of 4 that's gonna flower on its own. To properly work a line if I was breeding, I would only continue working with the 1 that did autoflower. This would need done over several generations until I wind up having them all autoflower.
I know puff puff pass has been attempting to get on here as a vendor, but until they do all the work necessary to get a true auto, I wouldn't recommend them