I don’t know what country you work in it might be worth doing an anonymous tip-off to your local competition authority if you’re in Europe. A software product providing affordances for tacit collusion would have a high bar to clear. It might be worth it if it’s even sold in the EU somewhere.
We need a law that would make wage fixing a crime with harsh sanctions and better data from IRS about wages.
Here is a free statup idea. Create a better version of Unions that would maximise people's earning potentials and improve working conditions.