Citation? Humans are not constantly moving their heads to the degree that chickens do, and I find it doubtful that the micro movements from our head (which our eyes have to adjust for with the vestibulo-ocular reflex so things aren't blurry, similar to image stabilization in cameras) are large enough to infer depth.

I never said people are moving their heads like chickens.

But we do move our heads around pretty frequently. Enough to build mental records of what the bounding boxes are going to be for a range of objects.

We're not doing that while driving, though.

If we're talking purely about going off memory, there's no reason why machines couldn't build up a similar catalog (which could be used by every self driving AI once learned). And human ability to judge distances varies significantly between drivers.