You don't need lots of different models of cars, I think we actually more on the same page than you think. I think there needs to be some variation because often vehicles are someone's work platform.

I do think it should focus on more sedan frames which are smaller and best suited for everyone but you still need truck and van frames, and having unified parts would make it very easy to share across the platforms. And it doesnt have to be big trucks or massive machines because not everyone needs that. Kei trucks for example are pretty big right now and very practical. All the cars due to aero dynamics have become the same shape anyways, just make like 5 standard frame, standardize all the parts and then just focus on battery improvements, electronic motors, the important stuff. Also everything should be mechanical first, door nobs, switches, steering, etc.

Going to have to disagree with you on the saftey stuff. You should have a moderate amount of fear when driving and still feel the need to turn your head when merging, or not feel encouraged to text on the free way going 90 mph because you have lane assist. Not only that but their attention is now being split between the road and a entertainment dash board screen that they some how expected to interact with for everything in the car(including features you need to drive the car), but also not while driving. I wouldn't compare that to being against the seat belts as I want people to be more safe not take the path of least resistance because now they have an excuse not to do the bare minimum which is just being present when driving. A more accurate comparison is I don't want people to take off their seatbelts because its legal now, because elon says self driving is safer than a human driver. I don't want people falsely lulled into a false sense of security thinking they no longer need to be present or mindful because they're in a large protective bubble that gives the illusion its protecting you.

But ultimately with your last paragraph I think we kind of end up with the same goal and vision, most people would be happy with a easy car they don't have to worry about. Its a lot easier if all the parts are standardized and meant to be interchangeable for all american vehicles. You could take it to any mechanic and it would likely be half as expensive and twice as fast. Might be as fast as getting your tires replaced at Costco in some cases.

And hell if it was done well even if you where piss poor and slow you could follow a YouTube guide on how to fix it with just a standard socket set and a screw driver. I'm piss poor and dumb and I fix my own car not because I want to but mainly because its increasingly becoming more expensive. Taking that away from people is like taking away their autonomy to address a problem in times of need or adding flexibility to it. Maybe they have a family member that can fix cars for less, or can get the part cheaper from a third party, or you fabricated/3d printed yourself.