From boat turn-backs to the GST debate, Australia's main political parties seem to have a universe-warping power to avoid consensus even where it actually exists and to talk about anything other than the main issues, writes Annabel Crabb.

One of the most mind-bendingly infuriating aspects of the political process just now is the bipartisan tendency of our federal representatives to - when presented with a major issue - immediately dodge it in order to argue about some tangled ancillary point about which no one with a pulse could give an actual damn.

It's mesmerising.

Take the news, for example, that Bill Shorten has decided to support the Coalition's policy of turning back asylum seeker boats.

Now this is a pretty simple story. It's not an elegant one for Labor, which has spent a decade and a half now twisting miserably on the hook of this diabolical policy area.

What would you expect from the Government in response?

A brief but satisfying round of "I told you so", followed by the indefinite satisfaction that comes with the capitulation of an adversary, or having been vindicated in a notoriously dicey judgment call?

Dear God, no. Immigration Minister Peter Dutton took to the airwaves straight away to declare that the main problem with the Opposition Leader's new stance was that he didn't mean it.

Mr Shorten didn't mean it, Mr Dutton argued, because of the words he used. Or because Labor's changed its mind so many times on this stuff that any new stance is by definition suss. Or because Tanya Plibersek is waiting around with her own inflatable life-raft to personally rescue asylum-seekers on behalf of the Labor Left.

As the Immigration Minister concluded that Mr Shorten's announcement was "absolute music to the ears of people smugglers in Indonesia and across the Middle East", birds fell from the sky, knocked stone-cold unconscious by the Australian political system's universe-warping power to avoid consensus even where it actually exists.

The value of this fight to the Coalition - not to win it, but to be seen every day to be having it - is most conclusively proved whenever Labor tries to surrender, and isn't allowed to.

Not that Labor is without fault in this national game of "pick a giant issue, then knock yourself out arguing about something else".

Could there be anything stranger than this week's to-and-fro about the GST, in which a substantial debate about one of the primary instruments of national taxation policy is led by two state premiers while both federal leaders pretend to be looking for something they've just dropped under the table?

Mr Shorten's response has been to embark upon an unwieldy argument about why NSW Premier Mike Baird would suggest an increase to the GST; Mr Baird was bullied into it by horrible Mr Abbott's last budget, which made some long-range forecasts of reduced federal payments to the states, forcing premiers to beg for a higher GST.

Now, that may well be true.

But are ordinary people more interested in hearing a range of opinions on whether Mr Baird's suggestion is a good one, or a range of opinions on why he suggested it in the first place?

The Prime Minister, meanwhile, has congratulated Mr Baird on his fortitude in raising the matter, without going so far as expressing much of an opinion as to whether it's a good idea.

Getting on for two decades ago, prime minister John Howard decided that he would make the case for a goods and services tax. His colleagues were divided between being impressed by his political courage and terrified for their own fates. He took the matter to an election, staked his political life on it, dragged it around the country for three years and didn't give up until a compromise version of the GST had been negotiated - line by line, pretty much - by an unlikely committee consisting of himself, his treasurer Peter Costello, and Meg Lees and Andrew Murray of the Australian Democrats, may they rest in peace.

Does anyone think it's realistic for that compromise to be this country's final word on the most comprehensive and relevant-to-everyone of all the taxes currently at our disposal?

Does anyone think it's weird that - 17 years after the election at which the GST was the biggest issue - our federal leaders now need to be nagged quite hard to express an opinion on it?

And that - given the chance to talk about something that matters to us all - they'd rather argue about just about anything else that doesn't?

Annabel Crabb is the ABC's chief online political writer. She tweets at @annabelcrabb.