The air, being a sparse fluid, can change fast. Especially so if another aircraft has flown through it recently. It's not that there isn't anyone there, it's the air they left behind is all non-laminar now. Doubly being suddenly downwind of stationary objects like towers, wind farms, and mountains.
Also, quick point of caution: One reason early flyers died a lot because they flew so low. Even after a few meters of height, just about any crash is likely to be deadly. Paradoxically, the higher you fly, the better off you are (in certain cases). In flying, your height can be measured in 'mistake recovery time'. The higher you are, the more time you have before you hit the ground, the more time you have to fix a mistake. If your engine cuts out, you have a longer glide time to look for a lake. You can get a fuel pump restarted or unfrozen. You have more time to grab a parachute and bail. Etc. It took a long time and a lot of lives to realize this. As such, personal drone-choppers will be more dangerous and I fear we will have to re-learn the lesson of height being a friend in aviation.
In the end, I still fear tech like this will not be as stringent as needed.