And those "millions" of reasons all boil down to R&D costs. Reliability, inspections, takeoff-to-landing autopilots (they exist - have existed for over a decade - for military helicopter drones), etc. are all cost issues which are slowly being worked on.

The progress could be faster if it didn't rely on angel and startup-style investments and the associated NDAs and trade secrets, but I don't expect that to happen in today's political environment.