"if I need to register and license my car, motorcycle, boat, plane, etc..."
I highly doubt you need to take an RC car to your DMV and get it registered. You almost certainly don't have to do so even for some manned coneyances (bicycles, electric bicycles in a growing number of jurisdictions, vehicles never intended to be used on public roads, etc.).
Trying to compare a toy/hobbyist drone or RC plane to a full-blown car (let alone aircraft) in terms of responsibility and registration requirements is patently absurd.
I think part of my concern is that this sort of regulation implies there's no such thing as private airspace, which means that even something as relatively-harmless as putting up a shed is a "danger" to aircraft and subject to FAA regulations by this exact same logic. Oh, and if you want to fly a kite you can, well, go fly a kite.
Realistically, trying to enforce control of airspace below 100ft over private property is going to be a fool's errand at best. That's space that ought to be fair game for unregistered aircraft (at that point I'd hardly call them "aircraft" anyway).
There IS private airspace indoors (it is why drone races typically happen in warehouses or stadiums). Outdoors, there is no private airspace so much as there is Class G airspace which is all airspace under 1200ft as long as you are out of range of any landing strips/airports, or under 700AGL if you are near certain larger airports. It is not legal to fly any manned aircraft in class g unless either transiting through to land/takeoff, or if you have clearance. However, it happens fairly often (just look at sightseeing helicopters as an example). A common problem with drone hobbyists is that they don't know anything about commercial airspace. Much of the concern has been about flying near airports where transiting low-altitude space is necessary. If drone operators had been assiduous in avoiding those areas (as RC aircraft operators have been) then this would be less of a concern.
I agree though, that there is very little possibility of enforcing low altitude airspace rules, unless they force some kind of software/transponder system into use. even then, the home-built drones are just too easy to make to guarantee it.
I highly doubt you need to take an RC car to your DMV and get it registered. You almost certainly don't have to do so even for some manned coneyances (bicycles, electric bicycles in a growing number of jurisdictions, vehicles never intended to be used on public roads, etc.).
Trying to compare a toy/hobbyist drone or RC plane to a full-blown car (let alone aircraft) in terms of responsibility and registration requirements is patently absurd.