Natalie Collins' comments come after Nicola Thorp launched a petition calling for a change in the law so companies could not force women to wear high heels.
Ms Thorp was sent home by temp agency Portico as she arrived for a shift at PriceWaterhouseCoopers in flats rather than heels.
Her petition reached 100,000 signatures in less than two days, meaning MPs must now legally discuss the issue in Parliament.
She said on Twitter:
Thank you for all of your messages of support. Please tweet @whoryouwearing (my woman's rights campaign) and share your own stories X— Nicola Thorp (@MissNicolaSian) May 12, 2016
Natalie Collins told Premier's News Hour: "What this is talking about is actually beauty standards and not about what is going to enable people to do their job better or to keep themself safe in their job.
"It's not acceptable to be insisting women wear shoes which are uncomfortable and potentially painful and cause health problems as well.
"It's a great concern... The fact it's only just been raised suggests that women are not confident in challenging things when they realise that they're wrong, potentially."
Portico said in a statement: "We are totally committed to being an inclusive and equal opportunities employer, actively embracing diversity and inclusion within all our policies and procedures.
"We are therefore making it very clear that with immediate effect, all our female colleagues can wear plain flat shoes or plain court shoes as they prefer."
Listen to Premier's Antony Bushfield speaking to Natalie Collins on the News Hour: