A recent study found that it is up by more than 20 per cent since 2001.

And it's worsened as a consequence of our rental affordability problem. The rental issue is itself linked to increasing inequality, which I'd describe as a "wicked" problem.

Yet homelessness is also one of the very few problems Australia faces that has a simple solution.

If we build more social housing, homelessness will go away. All we need is money.

The problem is not that the solution is difficult but that it won't pay off within one term of government, and governments of all persuasions are thus reluctant to invest.

Getting around that might involve tapping something that's worked before, something that brought us both the Sydney Harbour Bridge and the Opera House - a dedicated national lottery.

Most of us would be happy to kick in $10 for a good cause coupled with a chance at an immense jackpot.

If the Vinnies' CEO Sleepout, which combines a good cause with a dynamite gimmick, can bring in more than $7 million a year, think how much more could be raised if the donors were lusting after their own mansion, country house or chateau.

The idea has come up several times in recent years. In 2015, the Turnbull government's then Environment Minister Greg Hunt suggested a lottery to fund environmental projects.

That proposal was never discarded, but it melted away from government priorities to the extent of being entirely unmentioned two years later when the same Greg Hunt, by then Sports Minister, proposed an identical national lottery to fund Australian Olympic sports.

Now that we've found solutions for the environment and the Olympics, then, we can turn to the homeless.

Ah, not quite. Because both of those proposals went down without a trace.

The government thought, as I do, that a lottery would be a good money maker that would be generally popular with the great Australian public.

They didn't sufficiently take into account that the great Australian public isn't the body that has to be persuaded.

The elephant in the room is Tatts, and it thinks you're trying to take away its peanuts.

At the moment, just about every lottery ticket sold in Australia is sold by Tatts.

Tatts is a billion-dollar business, and it makes a motza.

It also pays billions in taxes and licence fees, which gets it the ear of governments.

If it trumpets (behind soundproof doors), our rulers listen.

But surely even Tatts believes in corporate social responsibility.

It might even share in a bit of the money. Note that I said "a bit" - the bulk has to go to building houses for the homeless.

We're not going to get a "Homelesslotto" unless Tatts gets its cut.

But how hard would that be to arrange?

It'd be useful, after all, to be able to tap into the existing over-the-counter sales system.

If we can launch the idea, we can nail down the detail later.

You'd need some kind of guarantee, of course, that the states wouldn't just cut their current social housing budgets to compensate.

You'd also need to put some money aside to go towards helping problem gamblers.

Doing that would probably reduce the number of homeless in the first place, so it's a win-win.

But that's do-able too.

If we can't find a way to get adequate funding for a national emergency that's troubling governments across the country and the world, what does that say about Australia?

Can't we make anything work properly now?

Greg Hunt isn't minister for housing this time around - but he is the minister for health, and given the various health problems that arise from regularly sleeping rough, his portfolio would cover it nicely.

Come on, Greg, let's give it a go.

In fact, I'll take two tickets.

Denis Moriarty is group managing director of OurCommunity.com.au, a social enterprise helping the country's 600,000 not-for-profits.