Surprise, surprise:
Connections between filtering software manufactorers and conservative religious groups.
In the US, censorware is mandated by law in public schools; and while firms
keep their blocked lists a secret and downplay connections to religious groups,
it's likely that school students' access to the Net is shaped to conform to
religious-Right ideology, with sites about everything from non-traditional
religion to sexual orientation being blocked.
The same Fundamentalist-linked firms provide the mandatory censorware
required to be supplied with all ISP accounts in Australia, which
probably suits Senator Alston just fine.