Why haven’t we legalised marijuana already? It’s a question brought to mind after reading Fairfax crime writer John Sylvester’s recent report on Melbourne as, in the words of assistant commissioner (crime) Steve Fontana, “the engine room of the country’s cannabis industry”.

Sylvester takes the reader behind the scenes of the old-style anti-pot crusade being waged by Fontana and his men, as “detectives from the Drug Taskforce […hit] crop houses at a record rate”.

Squint a little and it could be Chicago in the 1930s, with prohibition-enforcing lawmen pledging to take down the syndicates.

“We are determined to break the back of this industry,” says Fontana, like a modern-day Eliot Ness.

Well, we know how that movie ends. Prohibition didn’t work for alcohol and it’s patently failing for pot.

For evidence, you only need to look at the US, the spiritual homeland of drugs hysteria.

In 2011, Alabama police caught a man called Lee Carroll Brooker with three dozen dope plants in his backyard, grown to treat his chronic pain. Under the state’s anti-drug mandatory sentencing policy, the judge had no choice but to send Brooker to jail for life – with no possibility of release.

Yet here’s the thing: even in conservative America, the times they are a-changing.

Eight states now allow recreational marijuana – and many others are scrambling to join them.

That’s because the legalisation of weed in Colorado and elsewhere hasn’t brought the sky crashing down. Those Americans able to buy their pot from a chic dispensary rather than a seedy biker gang aren’t all inflicted by reefer madness. On the whole, the experiment has proved remarkably successful, with no spike in drug consumption, no increase in traffic fatalities, and – as you would expect – a marked decrease in drug arrests.

The Drug Policy Alliance explains: “Arrests in all states and Washington, D.C. for the possession, cultivation and distribution of marijuana have plummeted since voters legalized the adult use of marijuana … saving those jurisdictions millions of dollars and preventing the criminalization of thousands of people.”

So where’s the push for legalisation here?

Sure, we’ve seen very, very tentative easing of restrictions on marijuana as a treatment, beginning with Victoria’s Access to Medical Cannabis Bill 2016 and then spreading across the other states.

But there’s no sign whatsoever of a shift in respect of recreational use. On the contrary, anti-drug enforcement’s ramping up everywhere, as the Sylvester piece reminds us.

The lack of interest in the American example is particularly strange given Australia’s infestation by self-styled libertarians, forever popping up on the ABC to bray about the nanny state.

The besuited young men introducing themselves as “classical liberals” – where are they as the classically illiberal war on drugs drags hopelessly on?

Our inability to legalise marijuana – or even to hold a sensible conversation on the subject – provides a depressing example of a broader paralysis.

Michael Slezak recently published an article on how what he calls “a culture of extreme pragmatism” dominates debate about climate policy in Australia, with scientific advisers tailoring their reports according to what they think might be acceptable to politicians.

In Australia, we do things differently. In Australia, we judge what’s possible and then declare that sufficient.

The “small target” approach embraced by both major parties over the last decades means politicians now see even the mildest change as a terrifying gamble. Marriage equality; euthanasia; abortion; censorship: you can reel off a long list of areas where the status quo’s palpably broken and yet no one seems capable of providing a fix.

Legalising marijuana is the same. The abolition of anti-pot laws wouldn’t induct us into the Age of Aquarius. As we’ve seen in America, it’s actually a pretty small step – but it might spare a few kids from the brutality of the prison system, while freeing up resources that could be put to better use elsewhere.

More to the point, if we can’t embrace the mild and obvious reforms, how will we ever tackle difficult ones?