3D has the problem is that you can't just stop, wait and think if anything is totally weird. A self-driving car can pull over if it's confused, a self-flying plane can't.
Then again, self flying planes have been a thing since the early 1910s. It's far easier when you can just pick and altitude and heading and you're basically 99.9% in the clear that you won't hit anything.
In a car that approach will get you roughly a few meters forward, so it's incredibly hard to make a working car autopilot in comparison.
Well, usually it can stop, but if it gets confused during road construction where there's no shoulder to pull off to and it just stops in the road, you run the risk of a truck rear-ending you.
