As pointed in your link, NetBSD achieved this with some help from Debian. If I understand correctly, it's not that NetBSD tried harder, it's that their problem was easier: fewer packages which change less (they still use CVS, "stability" is an understatement!).

BTW, most Debian packages have reproducible builds. Those which have not (I'd say 5%) are shown in orange in the graph there: https://wiki.debian.org/ReproducibleBuilds

While we are bragging, stagex was the first to hit 100% full source bootstrapped deterministic and hermetic builds last year and the first to make multiple signed reproductions by different maintainers on their own hardware mandatory for every release.

Debian has come along way, but when Debian says reproducible they mean they grab third party binaries to build theirs. When we say reproducible we mean 100% bootstrapped from source code all the way through the entire software supply chain.

We think that distinction matters.

https://stagex.tools