Planes also don't evolve in an environment where most people only marginally care about the rules, where a significant minority is composed of unpredictable maniacs, etc. All in all I think it's more hostile for cars.

…of course, if we actually took road safety that seriously it’d be devastation to the entire car industrial complex. Because much of that industry is focused on design patterns that, in fact, cannot be done safely or sustainably.

every time I see a truck with a 4' hood line or a 21" touch screen in place of actual controls, I wonder when we're going to see another Nader, someone to strike out at the manufacturers for pushing shit that is unsafe at any speed.

Okay, so understanding that Boeing has been shipping airliners that boing instead of fly or have some bolts missing...

My dad was a frustratingly retired aerospace engineer because there was this period of the 90s where we actually did shrink the defense industry until 9/11 and the contractors started figuring out exactly how to "bribe" people. And one of his side complaints is that any aerospace engineer is probably actually good at being a general-purpose mechanical engineer, except that they've generally made the hard stuff actually safe earlier along, but nobody will hire them. His example being fully-automated-digital-engine-controls and fly-by-wire and having three redundant chains.

So, in the aftermath of the whole Toyota throttle-by-wire thing that really didn't go a whole lot of useful ways, I decided to check out his observation and I did some googling to discover a page where some big company was advertising to the auto industry at large their throttle controllers. And they talk about how they were built with "aerospace technologies" to be reliable and safe. And, looking farther along, it seems like that was not actually three redundant chains, just three threads of execution on the same processor.

Oh yeah, and generally any airplane that does have fly-by-wire and FADEC there is going to always be a set of reversion modes and people have to know about them. Obviously some aspects of this are far stricter because a car can just pull over to the side of the road... but also it needs to do that safely. Witness poor Anton Yelchin dying ignominiously because of the digital gear shifter thing on his Jeep.

But, yeah, the underlying problem is that the cultural expectation is to make cars that will go most places containing capabilities that a vehicle might never actually use in its entire service life and require the minimum amount of knowledge and basically zero knowledge above the collective cultural understanding of a car that's only mildly changed since a fully-mechanically-linked control system.

But why have drive by wire? Like you touched on, planes have orders of magnitude more testing, redundancy, and need. Not to mention maintenance

Is there a reason cars need it? Powered steering seems to be pretty effective with a better failure mode

I just got done swapping the electric power steering rack in my golf and let me tell you, it was nice to have a mechanical linkage when the old one died. It was also ludicrously expensive for just the part and would have been even more if I couldn't swap it myself. It's basically a sealed unit with no obvious way to service it. Some of this stuff is a trade of in ownership costs, and this wasn't even full drive by wire.