Here's something that most people don't know.
The United States is not the only place in the world where people exist.
Can you imagine how crazy it is for someone outside the US to want to buy a drone.
The mind is boggled!!
The discharge curve of a NiCad would make it a really crappy battery for drones.
The advantage of Lithium battery technology is the fairly straight discharge from full to zero. And the ability to juice the battery down to zero with near full output.