Love Freakonomics :)

That said I think Jury is still out on pay transparency mostly because there isn't that much practical data. The EU has been navigating it for a few years but research is still ongoing.

One paper (which is more focused on pay gap reporting, which is longer implemented and seems to have limited impact) suggests salary disclosure in job ads actually increases wages.

https://www.oecd.org/en/publications/pay-transparency-in-pro...

It's definitely obvious that internal salary transparency will a) act to normalise salaries over the long term and b) generally depress salaries. But disclosure at the job as stage is less clear.