"We've had radio controlled aircraft for many decades, with few problems; t"
The difference is that previously, flying a model aircraft took skill and nearly all participants joined a club and organization that had flying safety codes that members where expected to adhere to. The clubs operated a flying field that mostly limited hobby craft to a well known location and members could be tossed out for being reckless. Most parks ban model aircraft flying for the safety of other people using the park and to not have annoying buzzing engines all over the place.
Drones take very little skill to keep in the air and will often sort themselves out with the push of a button if the "pilot" gets themselves in trouble. Therein lies the problem. It's the sword vs. gun issue. A sword takes strength and skill to use effectively and a gun doesn't much at all. With a model aircraft, chances are that the first few times a new pilot takes to the air it isn't going to end well and they have to spend time and money to gain enough competency to keep the airplane flying for any length of time and to get it to go where they want it to. Fire up a drone and just twiddle the joysticks and most can generally manage to keep it up and flying in the general direction they want until the battery goes flat.