Re: WTF?
John savard "If a candidate has over 50% of the vote, he wins."
Sorry, what you describe is preferential voting for single member electorates. But what the article and the great Antony Green are describing is a counting system for multi member electorates, like NSW upper house or NSW local councils. AKA proportional representation.
The crucial difference is quotas. If a candidate gets more than 1/(vacancies+1), she is elected. Then her surplus votes above the quota get distributed to the candidate who got her 2 vote. If that 2nd candidate now has a quota, he is elected and the third prefs (from candidate 1) are now distributed. And so on until all vacancies are filled.
The question is: what are her excess votes? 1) Do you just put the ballot papers on a pile till you get to a quota, then look at the 2s, 3s etc of the next ballots you come across? 2) Or do you check all papers and then distribute the papers at a reduced value? (There is a formula but I can't be bothered looking it up now.)
Method 1 worked in pre computer days, especially for large (whole of state) electorates. Method 2 works in our present computer days. (The electoral commission does have to key every ballot paper into a counting system, but that can be done, even with Tasmania's Robson rotation or the ACT's scrimble scramble.)
But seems NSW entrenched method 1 just as computers started to take over in the mid-late 1970s.
Irish readers may be more familiar than US or UK readers with how to count ballots for multi member electorates. The Dail uses much the same system as Oz senate, local councils and Tas and ACT assemblies.