Fun fact - on most Linux distros any user program can see almost any event, yes including key presses, by reading from the right /dev/... file.

This is not surprising. The desktop Linux community reacted with hostility to the well funded security efforts (selinux, apparmor, grsecurity, etc)

Do you have any source for that claim? That would be a pretty serious security issue even unrelated to any security hardening (eg. on a multi-user system, one user could read out the password from another user — even with desktop usage, second user could be SSHed in).

As a datapoint, everything in /dev/input/* is owned by root:input on my Debian Bookworm install, and my main user is not a member of the "input" group either.

Biggest problem with most security hardening for Linux desktop is that it breaks the natural usage pattern: I store my files by their content, not by their format (eg. I might have a folder for my project containing image files, spreadsheets, FreeCAD files, maybe even some code or TeX/ODF files). If programs are restricted to access the entirety of my $HOME though, there is not much benefit to that protection since that's where my most valuable data is. If they are restricted to per-program folder, I need to start organizing my data differently and unnaturally.

Android mostly does not use the "files" metaphor and basically does exactly that (per-app data): coming up with a security model and file management UX that does both is where the challenge is.

Security is a tradeoff (fucking always...)

It's the same reason I choose to keep my front door unlocked basically all the time - I know my neighborhood, the risk is really low and the convenience is high.

Further... practically everyone agrees that they don't need bank vaults as front doors. It makes zero practical sense: The cost is incredibly high, and the convenience is very low.

There are ALL sorts of wonderfully cool things you can do on a system where applications are allowed to trust each other, and the system is permissive by default.

You can customize behavior more easily, you can extend software more easily, you can add incredibly detailed & functional accessibility support, you can create incredibly powerful macros and commands.

This is so important that fundamental OS design from the early 90s actually prioritized and catered to exactly this style of open, trusted, platform (ex - all of COM in windows...). This is what made personal computing a reality...

All of those fall flat when you try to impose "well funded" security efforts.

Those efforts have a place, in the same way that bank vaults have a place. Whether that place is a personal computer is a different question.

Implying those folks are hostile for no reason is... at best a woeful misunderstanding of the situation, and at worst a malicious mischaracterization.