Judging voting is complicated. The information here is drawn directly from theyvoteforyou.org.au
They exdplain their methodology here.
Basically legisaltion often has multiple votes on its way through Parliament. As the They Vote For You site
explains: "For an MP or Senator to be marked as "voted very strongly for" a particular policy, they need to
have almost always voted in a way that supports the policy (they may have voted against it once or twice,
but usually only in a less important vote) and they need to have been present for almost every vote (too
many absences will count against them and may even push them into the "voted against" categories since in
our Parliament, not voting ultimately has the same effect as voting against something)."