Without solid evidence, the story goes, it is not possible to easily advocate for change. This certainly applies to men and women receiving the equal pay for equal work.
And so, a major new international report has found the extent to which Australia's gender pay gap exists is far from complete with employers defying mandatory reporting laws and not being held accountable for reducing the gap.
And despite Australia being an early world leader in legislating for gender equality, the report, Bridging the Gap by the Global Institute for Women's Leadership (GIWL) at King's College London has ranked Australia equal last in a scorecard on the gender pay gap reporting across six countries.
The report's authors, included researchers from the Australian National University, were surprised to find Australia lagging behind comparable international peers, South Africa, France, Spain and Sweden to be equal last with the United Kingdom.
"There was an original expectation that Australia would perform higher than it did in practice," Dr Miriam Glennie told The Canberra Times.
"The system is so well known internationally."
From 1986 to 2012 employers had to provide qualitative assessments about what they were doing to support gender equality. The Workplace Gender Equality Act 2012 brought in by the then Labor government required reporting of the pay gap.
So what is happening that caused the low ranking?
There is a current national gender pay gap figure calculated, through industry benchmarking for full time employers, by Australia's Workplace Gender Equality Agency at 14.2 per cent. The Federal May budget cited the gender pay gap as 13.4 per cent. Take in all employees and the gender pay gap is more than 30 per cent.
Under commonwealth law, there has been a requirement for mandatory reporting of pay by employers to the Workplace Gender Equality Agency.
But this is still not the full story.
"It is clear .. aggregated data is not enough but actually more broadly data is not enough to drive change," Dr Glennie said.
"There needs to be somebody with more power in the mix deriving some accountability."
The current law requires non-public sector employers with 100 or more employees to submit an annual report to the agency - about 40 per cent of working Australian women. That is disclosing to the agency not public reporting.
"If we don't have access to that data then it is not enabling that indicator to be monitored in the way that the legislation designed it to be," she said.
There has been push back from companies for the burden of reporting, but it is usually for what is described as commercial or privacy reasons. Budget papers show nearly 11,500 employers reported to the agency in the last reporting period with almost 98 per cent compliance.
Dr Glennie says better performing nations in the "Bridging the Gap" study, such as France or Spain have follow through and accountability set into law.
"There are really high levels of mandated engagement and or negotiation with either employees or their representatives to make sure that gender equality, plans are developed," she said
"[In Australia] organisations are required to report the gap, but they're not required to disclose the gap and they're not required to act on the gap."
Buried in the May Budget was a Morrison Government promise to include the public service in gender gap reporting legislation. The women's statement declared that the amendment, if passed, would "assist public and private sector organisations to benchmark performance against each other."
"It's certainly going to be a benefit to capture a much larger percentage of Australian women in reporting," Dr Glennie said. "Including the public sector will capture a lot more women, and it will capture a lot more employers."
The government also announced the nine year old Workplace Gender Equality Act was under review. Expected to be completed by the end of this year, the review will consider ongoing employer reporting obligations.
Labor policy, if it wins office, pledged to audit the gender pay gap in the public service and legislate so companies with more than 250 employees report their gender pay gap publicly. The opposition has also promised to ban pay secrecy clauses and give employees the right to disclose their pay, if they want to.