I wish there was more appreciation of how difficult reproducible builds are and unwinding the decades of non-reproducible cruft that we have built up.

Commenters on forums and issue trackers often seem to think like it could all get done tomorrow, when large projects like this, which even have it as one of their core competencies, find it difficult to do and aren't done yet.

> I keep reading people making this claim repeatedly on orange-site

If this is suppose to mean HN, the header color is blaze orange https://chir.ag/projects/name-that-color/#FF6600

Is this still true if you use flakes to build NixOS?

Yes, Nix doesn't actually ensure that the builds are deterministic. In fact it works just fine if they aren't. There are packages in nixpkgs that aren't reproducible: https://github.com/NixOS/nixpkgs/issues?q=is%3Aopen+is%3Aiss...