Other answers have addressed why there are anti-Islamic parties in Australia.
Why are there several anti-Islamic parties in Australia?
Splinterism, an endemic issue with extremist parties, and movements in general preoccupied with ideological purity rather than electoral success through coalition politics. Communism is even more notorious for splinterism, after all.
Latest instance I can think of: the United Patriots Front has splintered from Reclaim Australia, because Reclaim Australia wasn’t monomaniacally anti-Islamic enough.
But if we go through AIJAC’s list, we see another reason: anti-Islamism is not a defining characteristic of many of the parties listed there; it’s just a common attribute of populist right/far right groupings.
- Pauline Hanson’s One Nation: anti-immigrant, rightwing populist. (East Asians were her bugbear twenty years ago.)
- Australia First Party: neo-nazi.
- Rise Up Australia Party: Christianist. I can’t imagine a Sri Lankan heading up the United Patriots Front, after all.
- Citizens Electoral Council: LaRouche-ist. How the hell I ended up on their mailing list is a mystery to me.