I'm not following those edge cases at all

Understood. So I will explain a bit more in depth. But, the things I laid out are pretty basic. The dynamic responses of a vehicle under motion works something like this.

(1) Balance. The car is never level. As you accelerate, there is inertia. The drive train and the chassis do not move in unison. They are connected by "Springs". This is like an airplane: attitude. So, the forces on the car and the road are different, but related. And there is a lag.

(2) Dynamics. Accelerate, nose up + ass down. Decelerate, nose down+ass up. The road is not straight? Similar for a turn (tilt left, tilt right). Now, combine. What happens? There is a dynamic weighting applied to all 4 corners. Go into a rt turn? Weight front left. Unweight rear right. etc. So, the point is that the friction is changing in each corner as you drive. The friction must exceed the energy of the car, or you will slide like on ice, etc. But, for the reason you brake in a turn, this is not always guaranteed, etc.

(3) Topology. Now, add some complexity: The road is not flat. This changes the calculation of the weighting for each tire. A tire on a 45degree incline is not holding as much friction as on a 2 degree one. This is like standing on a sand-slope, etc. Just basic idea. Now, The traction is a function of the weighting of each tire, plus the relative position of the tire to the road surface.

(4) Environment. Also, you have to consider a few other things: Do you know the co-efficient of friction of the road surface? Clean? Dry? Wet? WIth autumn leaves? What tyres do you have? What is the friction curve with relation to the rubber type and the ambient air-temperature? Oh, and by the way where is the tread depth? Today? Yesterday? These are all things that go through the mind of a trained driver and are not un-common knowledge (think: f1, rally). Same thing with left-foot braking, not using ABS, non-abs brakes on snow/ice/dirt/ etc.

(5) Complex System. If you cannot predict any part of this, you run the risk that the inertia of the car from speed etc >friction => loss of traction, accident, crash etc. This means: If you don't know the "camber" of the turn, your math is a problem. You might know that you are turning right at x degrees, but what will the turn be in 100m? constant radius? or not? What if you change lanes in the turn? etc. Now, you can topo-map solve this at high enough resolution. Eg., something akin to a race-track, in a video game. Go to Laguna seca, and put that in a computer. Problem here, though, is scale: like 1 inch topo variances or something, but that data set for CA state? Is huge. You don't have it. How would you even get it? What is your other option? Terrain acquiring radar? That might work. There is probably something in 60ghz and up that in theory might work. But you are line of sight constrained and now how far out can you look? 10m? What is the system's reaction time? How fast are you?

(6) Road hazards. Similar problem here. If there are abrupt changes. How do you acquire them? A sinkhole. A pot-hole (might break your wheel, etc) These are things not on a map-set. A live person just drives around them. But, what about a freeway? 6 Lanes, everyone is packed in like sardines. Does the guy in lane 6 know the guy in lane 2 is going to swerve? If he doesn't swerve (an breaks his wheel) what happens? The bridge failures are an example similar. If you are driving, you just look and see: no road. But, what if you are on auto-pilot? Who tells the computer there is no road? Same thing flash flood. Even worse, is hydroplaning risk (like 1/4 inch of standing water, say). If you are not driving are you paying attention? If you don't feel the steering wheel, how do you know? Can you put that into the computer?

That being said, they are doing amazing things with traction control systems on motorcycles right now. So some of this may get figured out. But you will not see a guy with all of this tech riding no hands/no brakes, etc. This is strictly in addition to user input and continual monitoring of the controls.

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The Interstate System

Do you have experience actually navigating? Like, say long stretches accross the USA? At continental scale? The Interstate systems is what it is. Its "90%" done. There is not 1000 mile segments being built. Max is 100 miles, and even that is incredibly difficult (permits, etc). Also, those are not "capacity" related build outs, you are talking only a couple of missing geographic links. New lanes/etc are a different animal (thats maintenance, for the most-part). Put another way, US is not going to rip out 2/3 of the roads and put 3x the traffic on the smaller footprint, to get to a break-even case. Now, you want to increase by 278% more cars/hours on the system? OK fine, but it will cost you. Its basic math, no? Also, the economics of construction don't work out that you save money by only "fixing" half the lanes or whatever. Lastly, consider the purpose: more capacity? History shows, no matter how many lanes you put down, the 405 fwy will be in Jam at 4-6pm in LA. Its not just rubbernecking. It is a larger social issue: people will procrastinate. Now they are in a "hurry". Oops. [As the saying goes, sometimes there is no engineering around stupid =D.]

Other Safety cases.

The point of these cases is not that they are per-se fatal. It is that they require real-time rapid-terrain-acquisition to avoid making the problem worse. Deer is similar. I doubt a basic Lidar is going to acquire a deer in the brush that jumps out in the road. It might, with thermal imaging, make it possible to see hiding off to the side. But, the calculation would need to be predictive in a what which is pretty amazing.