They're somewhat of a Canberra institution. Rain, hail or shine they're there; squeegee in hand.

Tales of windscreen washers at traffic lights are the stuff of legend in the ACT. But what is less well understood is just how strange that is.

A quirk in the ACT Road Rules has meant Canberra is the only place in the country to allow the practice known as "roadside commerce".

Elsewhere it is either banned or paying someone for it is banned.

The Australian Pedestrian Council's Harold Scruby is unimpressed.

"Few things catch me by surprise these days; we're a very funny nation," Mr Scruby said.

"But no, out goes the ACT with one of the most absurd pieces of legislation I've seen in 25 years of road safety."

Up until about 10 years ago windscreen washing on a road in Canberra attracted a fine.

The former Labor government minister Terry Connolly was unapologetic for that tough stance.

"If the government sat back and did nothing and failed to enforce the law, when the first young person was killed or injured we would be held to account in this Assembly," Mr Connolly told the Legislative Assembly in 1993.

"We are not prepared to do that."

Squeegees seized by WA Police after four windscreen washers were charged over an alleged confrontation with a female motorist in February 2015. ( @BelmontPol )

Two years after the ban was lifted on window washers, the ACT coroner called for them to be banned again after finding the death of Lorraine Brown, 56, was in part due to the distraction caused by having her windscreen cleaned at an intersection in Red Hill.

Ms Brown died when she drove off from the intersection and a truck with faulty brakes slammed into her car in 2003.

Calls to ban windscreen washers at traffic lights occur regularly in the ACT, and at times have even stemmed from the Government itself, but they have never progressed much further.

Why was the ban lifted?

The current ACT Government does not actually know why the law outlawing window washers was lifted, but said it had no plans to change the legislation.

It was an earlier Labor government, the Stanhope government, that changed the law in 2004.

Then Labor minister for urban services Bill Wood had the changes passed through with little fanfare among almost 40 other amendments.

The only official explanation given was that "new regulation 22A permits the roadside activities prohibited by (the) new Australian road rules".

The replacement of the words "must not" in the national legislation with "may" allowed the new legal industry in Canberra to be born.

The Pedestrian Council's Mr Scruby has urged the Government to revisit the rule.

"These are the sort of things you see in Asia, where the death toll is two and three times greater than Australia, and that's why... because it's dangerous," Mr Scruby said.

People washing windscreens at an intersection in Canberra. ( ABC News: Ewan Gilbert )

Mr Scruby said pedestrian safety aside, the effect on a motorist who injured someone working on the road could be devastating.

"You hit that person and under ACT law it seems (windscreen washers have) got the right of way," Mr Scruby said.

"How would you feel if you were suddenly in front of a magistrate having to defend such a ridiculous piece of legislation?

"Why should motorists and other road users be put in that position when 99.9 per cent of (windscreens) don't need cleaning or can be cleaned with the press of a button?"

Outside of Canberra, police have regularly reported being called to crackdown on donation collectors and windscreen washers at traffic lights, and said complaints of dangerous activity, harassment and intimidatory behaviour were commonplace.

But the experience in Canberra was not always negative.

Several ACT politicians have said the law opened up a job opportunity for some of those who may not otherwise have one.

A number of charities also credited weekend window washing drives with helping them raise much needed funds.

But Mr Scruby cautioned against relying on such arguments when making laws.

"Let (politicians) look at the risk," Mr Scruby said.

"What is the risk of a child standing in the middle of the road cleaning windows when the red lights are going? Not, has anyone been killed?"