Sometimes that is a contract requirement.
Geissele was until recently prohibited by contract from selling the 10” Mk4 rail they made for the FBI duty guns. Apparently there has been a small change to the GKV rails and Geissele got a waiver to sell the blems.
The commercial 19x did lack the manual safety. Glock has never sold manual safety guns commercial only to LE/Gov customers who mandated them.