Creating a self driving car which can navigate a dark, rainy parking lot is something we do not know how. Not even in theory. You can't just throw more compute at it. You can't go from a Vickers Type 464 bomb -- one of the most complex bombs in WW II -- to the "Little Boy" by just putting more explosives in there.
Level 5 driving just means it can drive a child or blind person around who can’t take over in an emergency. That’s the difference between Little Boy and a Moab.
However current level 5 cars aren’t something a consumer would buy. A car that refuses to drive in 99% of situations isn’t marketable. The minimum threshold for that might be a car that can only drive in Hawaii, not a large enough market to pay for R&D, but still plenty use for a blind person living in the area.
No, that's what level 4 means. Level 3 can rely on having a driver to switch to, level 4 can't.
The difference between 4 and 5 is that 4 can park and give up under arbitrary circumstances, while 5 has to be able to keep going almost always.
Geofencing is part of the criteria, but a car that can only drive in the USA but can’t drive in Europe still qualifies as level 5.
Similarly a car that refuses to drive in a blizzard but can do everything else is level 5. Being able to drive at night or moderate rain is mandatory however.
That said, there is plenty of slightly different definitions thrown about. I am sure someone is going to argue a car needs to be able to drive in any country to qualify etc etc.
Level 4 cars need a steering wheel to be generally useful. But a limited vehicle like a taxi doesn't need a wheel, no matter whether it's 4 or 5.
I agree with the rest of what you said. Geofencing entire continents isn't about driving ability, and blizzards are an acceptable human-level restriction.
However it looks like this just changed: https://www.nhtsa.gov/sites/nhtsa.gov/files/2022-03/Final-Ru...
“For vehicles designed to be solely operated by an ADS, manually operated driving controls are logically unnecessary.29 To account for this, the NPRM proposed a regulatory scheme in which the affected standards would not assume that a vehicle will always have a driver’s seat, a steering wheel and accompanying steering column, or just one front outboard passenger seating position.”
They are apparently allowing level 4 Taxi to be considered full ADS even if they have additional “Stowed controls” options.
https://unece.org/DAM/trans/doc/2013/wp29grsp/WP.29-161-18e....
I do not recognise the reality you are in.
Navigating dark and rainy parking lots is not hard. At all. Not hard in theory, and not hard in practice either.
We have lidars which work very well in rain. We have cameras with excellent dynamic range. Parking lots are slow environments where everyone moves slowly and you are generally allowed to stop if you are suddenly spooked or need a bit more time to check things.
There are hard problems about self driving cars, but dark and rainy parking lots are not the stumbling block.
Where do you even get this idea?
Let me tell you two harder things about self driving cars: "How many nines do you want in your certainty that the car won't hit anyone?" and "How do you want that proven? With stats or with fault tree analysis, or a mix of both?"
They're level 4 with very severe location and weather limits.