[rcxdude]

Yes, but the radar has poor angular resolution (but a good idea of relative velocity), so it cannot tell the difference between a stationary object at the side of the road and one in the middle of it, so it must ignore all stationary object (by ignoring all objects with an apparent velocity approximately equal to the speed of the vehicle) in order to avoid constant false positives.

[chinhodado]

Can you explain further what "poor angular resolution" means?

[JackCh]

It's good at determining whether something is moving towards it or away from it, but bad at determining where that object is; whether it's directly in front or slightly to the left or far to the left. Its "vision" in that sense is blurry.

[semi-extrinsic]

That if Tesla were to release a side-by-side comparison of a regular photo versus what the radar sees, people would be screaming bloody murder.

Imagine an image smeared out like on a 15 year old Nokia picture phone, but with very high colour(velocity) precision. That is what a radar sees.

[cbr]

Poor angular resolution means you can't tell if an object is at 12 o'clock vs 1 o'clock. It means you can tell there are things, but you don't accurately know what angle they're at.

[codedokode]

It cannot see small details. So it probably "sees" another car as a blurred spot and only when it is close.