Why don't we have driver assist technology? Some camera and stuff to alert drivers, before we go all out for autonomous cars?
Already there for high end cars as optional packages.
Audi has a lot of optional ADAS technologies available, including radars, thermal cameras, etc.
Honda has this HS (Honda Sense), and I think other car manufacturers have similar things.
On this year's CES, just laser radar technology itself has 16 manufacturers showing off their latest cool device.
NXP has their mmwave semiconductor for radars years ago, and TI unveiled their all-in-one mmwave SoC in 2017.
So yes, there are a lot of ADAS even long ago, just not popular in cheap cars.