Ann: Notice of General Meeting/Proxy Form, page-19

I just had a dive into the Australian Corporations Act 2001. Acording to section 1.5.1 it looks like they actually need 75% of the vote:

"A special resolution must be passed by at least 75% of the votes cast by shareholders of the company entitled to vote on the resolution and who vote at the meeting in person or by proxy (if proxies are allowed). The sole shareholder of a company may pass a resolution by recording and signing their decision. A company must keep a written record (minutes) of the members' resolutions and meetings."

I'm not a lawyer so take this with a grain of salt. To me the above reads that they only need 75% of votes actually cast which is not the same as 75% of the total possible votes. i.e. if enough people are lazy and don't vote then the resolution may pass with just the votes they have.