I think i'll try nail two issues at once (only briefly skimmed over everything).
People say the Greens got Pauline Hanson elected because they changed the senate voting system. This is utterly false slander by those with a desperate crabs in a bucket mentality. The new senate voting changes mean that parties can't negotiate lists in secret and without the input of the voters, lists which in the past have gotten total wild cards elected (Jackie Lambie, Ricky Muir, The LDP). In some aspects, these people are as extreme as Pauline Hanson
So, it's clear our voting system can produce unexpected outcomes. The new changes put the power of the preference flow back into the hands of the people rather than arcane "preference whisperers".
Here's the real reason Pauline Hanson got elected - because people voted for her. There was no Greens, Liberal or Labor tricks, no party is to blame. She recieved 9% of the vote, almost 1 out of every 10 voters preferenced her first.
Democracy is not to produce good outcomes, democracy is outcome neutral. All democracy is designed to do is represent the will of the people and by Pauline Hanson getting elected, the will of that 9% is represented, this outcome is democratic. The attack arguments Labor is running against The Greens are anti-democratic in that they think that if 1 in 10 people vote for someone, somehow, its a mistake that person gets a spot.
I hate many of Pauline Hansons policies but to ignore the fact people voted for her is a total fantasy. These people voted for her for a reason. Something the main parties aren't addressing, a fear, an idea, a belief. If the major parties (or indeed, *all* parties or society as a whole) doesn't address the concerns of these people, forces like Pauline Hanson will grow and grow.
We're seeing it all over the political world with people like Trump. Trump, however, predates the wider movement we saw even earlier in places like Greece (Golden Dawn) or many other European nations where the top two parties of the previous 50 years are no longer the top two, because they felt establishment, they ignored fears and concerns people were voicing. The major parties need to start listening to 9% that voted for Pauline Hanson and figure out what to do with them, to simply ignore them is a very dangerous thing indeed.