Then wouldn't you see businesses fighting for it instead of against it?
A trend I noticed from all the EU regulation concerning business: you can be certain it will look like it's doing good for people and bad for business but it will just end up screwing common people and small businesses in favour of big businesses.
Think about VATMOSS: great, now Amazon can't charge Luxembourg VAT to customers in France BUT small businesses need to keep track of every EU country VAT, apply it and retain 3 pieces of evidence of the customer location. In practice, small business killed their eCommerces and moved to Amazon or just swapped their payment processors for Paddle (which charges way more but handles VAT for you).
Think about GDPR: it was a money transfer from people to lawyers and businesses are still doing whatever data transfer they need just by adding more text to their EULA which nobody reads.
We'll see how this one goes - but it makes sense that more transparency will have a chilling effect on the cost of high performers who know how to negotiate.
Nobody has ever been able to define what equal pay for equal work means because every human being is different (skills, work ethic, ease of working with them, timeliness, negotiation skills, assertiveness, leadership ability etc. etc). So I can understand businesses playing it safe and just paying everybody less than trying to keep people who are good but more demanding of higher salaries.