Backing this up: automotive radar uses a band at ~80 GHz. The wavelength is ~3.7 millimeters, which lets you get incredible resolution. Not quite as good as the TSA airport scanners that can count your moles through your shirt, but good enough to see anything bigger than a golf ball.

For a long, long time automotive radar was a pipe dream technology. Steering a phased array of antennas means delaying each antenna by 1/10,000s of a wave period. Dynamically steering means being able to adjust those timings![1] You're approaching picosecond timing, and doing that with 10s or 100s antennas. Reading that data stream is still beyond affordable technology. Sampling 100 antennas 10x per period at 16 bit precision is 160 terabytes per second, 100x more data than the best high speed cameras. Since the fourier transform is O(nlogn), that's tens of petaflops to transform. Hundreds of 5090s, fully maxed out, before running object recognition.

Obviously we cut some corners instead. Current techniques way underutilize the potential of 80 GHz. Processing power trickles down slowly and new methods are created unpredictably, but improvement is happening. IMO radar has the highest ceiling potential of any of the sensing methods, it's the cheapest, and it's the most resistant to interference from other vehicles. Lidar can't hop frequencies or do any of the things we do to multiplex radar.

[1]: In reality you don't scan left-right-up-down like that. You don't even use just an 80 GHz wave, or even just a chirp (a pulsing wave that oscillates between 77-80 GHz). You direct different beams in all different directions at the same time, and more importantly you listen from all different directions at the same time.