I'm not sure they need endurance, if they're cheap enough companies can just buy a fleet n times larger than the number they need in the air at any given moment

I'm not sure they need endurance, if they're cheap enough companies can just buy a fleet n times larger than the number they need in the air at any given moment and have the others charging at base. Or more likely buy some extra batteries and have someone employed to swap them out when they're getting low.