What happens when someone dies because they couldn't avoid the accident because the car prevented them from going fast enough?
This is ridiculous. Speed doesn't cause accidents. The difference in speed does. So if the speed limit is 70, and that is as fast as you can go, then you'll still have accidents because someone will be going 45 or 50.
Also how much would you bet that 99% of those devices would be disconnected upon delivery?
If you look at the speeds people go on roads they are not bound by the speed limit, but rather from how comfortable people feel on the road. We have roads here where the speed limit is 50 mph, but everyone goes 70-75. If the speed limit was changed to 75, people would still go 70-75 because they feel comfortable at that speed. You wouldn't suddenly see everyone going 100 mph.
If this did ever happen I'd never buy a new car again. I'd just get an older one and spend 25K doing an engine rebuild.
Also a lot of the time tech like this is wrong when it comes to determining the speed limit. We have a new Volvo that has speed limit recognition. If you go over what it thinks the speed limit is it will warn you. However it always bases that limit on the last speed limit sign it saw. So if you are driving on a local road with a speed limit of 30 mph and then go onto a highway it freaks out for several miles until it sees a new speed limit sign because you are going 60-70 mph and it thinks you should be going 30 mph. Imagine if this new tech didn't let you accelerate onto a highway? You'd be dead.
All this new tech doesn't help. It just makes you rely upon it too much and not pay attention. I never spec any driving assist options on my cars. The driver should always be in control of the car. The car should not be braking for the driver or accelerating for them, etc. Certain options, like ABS are good because they help the driver brake when the driver wants to brake. But they don't brake when the driver isn't expecting it. The other tech mentioned in that article was having the car brake if it detected a bicycle or pedestrian in the road. Well what if it 'thinks' something is in the road and slams on the brakes for no reason and you get rear-ended? Another terrible piece of tech IMO. This stuff is nowhere near ready for a general release. Look at the 737 Max 8 as an example - tons of tech designed to help the pilot, and the planes crashed anyway (and perhaps because of this new tech.)