NZ got proportional representation elections, in the end, kind of by accident. With 1980s Labour PM David Lange misreading his notes and committing to it, and when Labour reneged, National leader Jim Bolger promised a referendum on it. Thinking kiwis would never vote for it.
Juggernaut talks about all this in s02e04;
https://www.thespinoff.co.nz/podcasts/juggernaut
What Juggernaut doesn't cover in any detail is the years of grassroots campaigning that preceded all this.