My eleven year old laptop is running Kubuntu. I think it might be a Camry (absent the insanely dominant popularity).

Now we're just missing Gentoo and Linux From Scratch

More like LFS

I'm a huge fan of immutable distros, but I'm not sure they're mass transit.

Maybe:

It gets you where you want to go, but you don't have to handle the toil of dealing with traffic.

You likely had it 20+ years ago, especially in the mountains. The Hilux pickup is fairly indestructible. Top Gear did an episode where they tried to kill one (linked below in other comments) and couldn't. It's rather impressive. I've seen the same exact model rolling around Africa and the Balkans today. ISIS fighters were known for using them as platforms for large-caliber guns. It's all about basic utility, stability, Toyota parts are easy to swap out, and adaptability to anything you feel like bolting on to it.

Same. As for distro, for me personally, it should be designed to be usable with one hand, because I crashed and broke my elbow.

For bike users in general though, it should be something ...bespoke.

For non-ebike cyclists I think an analog computer would be appropriate. Wait, do those have an OS? I guess it would be a manual system but I gotta check the manual manual to be sure.

My reason for the bullet train and subway in particular is the nature of being on tracks as well as avoiding traffic (Windows bloat in my use of the concept).

Great for the average user because they don't have to really understand any of the systems involved or anything, just pick a stop and off it goes, but if you try to go off the beaten path at all, you'll probably find yourself having to work around the immutable nature pretty quickly. You can't just go anywhere with it like you would a car.

There's a program that I had installed that for some stupid reason doesn't let you log out on the Linux version and it auto logins as well, so if you log into the wrong account like I did when I installed it, you have to delete the user data from it. In Bazzite, it turns out that you can't just go into the folder and do it manually, you have to use a specific application that comes with Bazzite to delete user data from an application. A minor annoyance, but I did have to go off the rails a little to solve the issue compared to how I would've handled it on Windows.

I installed Debian Linux for several computer-illiterate old ladies. They never had to look under the hood. They are very happy with it.

Yes. They shouldn't need to. Sadly some think everyone should.

Only as image in a hypervisor for pentesting.

That's ubuntu

hl2 car?