The Nix community has been at it for over a decade and they've only recently managed to repeatably build the NixOS ISO. The kind of determinism you're thinking about is a lot harder than you're giving it credit for.

It's still doable I think, and I'd love to work towards it, but who is going pay for it? Mountains of wasted compute day after day might feel like a waste to nerds like us, but to an investor it's opportunity.

Fixing it? Less opportunity.