20W meat computers with stereo mics and low-res HDR cameras are level 5 autonomous, don't underestimate digital ones.

The humans brains processing power for visual and spatial stuff is amazing. We may get there for computers one day - but we are not even close yet.

I don't know how "unnecessary" it is if we're talking snowed roads, country roads, roads that haven't been painted in a decade or longer, or if we're talking about autonomous cars without a wheel.

Under those conditions, it's pretty much Level 5 or bust. But yes, that doesn't mean Level 4 cars won't start getting adopted, especially if the autonomous systems are just another "feature" on a regular car (hopefully EVs in all or most cases).

Having to turn off self-driving features will be like losing cell service. It's not what you paid for, it can be mildly inconvenient, but you get over it and on with your day.