Do you have a source for that? DfM is pretty much always a worse option than multi-camera reconstruction AFAIK.
> almost every situation the car would cast a shadow to that featureless wall.
I think "almost every situation" a pretty low bar for automotive safety.
I don't know too much about what people do in the automotive world, but in robotics it's pretty common to have an IR pattern projector if you really need depth on featureless surfaces.
I think this can only ever be reliable with a projection. A pulsed line laser or something that is synced with the camera. Then again, a simple ultrasound sensor might do a better job.
Otherwise the system might work, but is much more unstable in non-optimal conditions. Robustness is a pretty important feature for driverless systems. That said, stereoscopy would at least be better than only one camera.
AFAIK, pretty much none of the driverless systems are using parallax. The reason why not is that parallax only gives good depth information at most up to about 10 feet. Disparity mapping is pretty limited in real life.
Instead they get depth from video.
I'd imagine in almost every situation the car would cast a shadow to that featureless wall. Although Tesla might not have a camera placed to a right spot to actually see that shadow...