Their carry weight is absolute shit and ferrying over 10 doses isn't really worthwhile
What you say is absolutely true about quadrocopters and octocopters. It is much less true about fixed wing drones.
You don’t have to go all the way to a Global Hawk to get reasonable carrying capacity. Even hobby sized stuff could be used for this reasonably well. Parts are easy to acquire, they are easy to conceal, you can launch them with a catapult like setup, they can drop off their load and fly back autonomously.
I bet that it is already happening or at least there are smugglers experimenting with the tech.
This had me thinking about homemade disposable rockets. Either use them for cargo, or attach one to a strong enough glider, so that it can reach the desired area, release the glider (that can use maps + GPS and sensors to land safely) then proceed for a while fooling whoever would follow its heat trail.
Not that I wanted to become a drug smuggler, just brainstorming. We will need all that stuff when the next reptilian invasion occurs:^)
It was a hybrid fixed wing drone that could carry 150Kg.
https://www.vice.com/en/article/dyvwmv/look-at-this-huge-dru...
In the case of the mule, the carry weight is relative to shit.