This has not seemed to be a problem for the countries using them; what makes the US so uniquely inefficient?
This shows that the US private sector can well produce contemporary drones on a compressed time scale.
It is the Pentagon which is not interested in overhauling settled vendor relations.
Ukraine deploys several million drones a year, you can't get there by mere artisan workshops in garages.
Sure, the designer teams back in Ukraine are lean, their members wear tracksuits and don't have a 50-head Human Resources to watch their behavior, nor three levels of managers wearing Philippe Patek above them. That is part of the efficiency and lower cost.
A basement lab can start making new drones as soon as you can get them the components. An assembly line will take months to get any new machinery it needs, set it up, ensure production works, figure out how to QA it at scale, etc.
It doesn’t matter if you can make 8 million drones if the enemy already has a way to counter that particular kind of drone. Eg I think Ukraine has been through a bunch of iterations as they adapt to Russian tank armor, jammers, extended range, etc.