– Here is a Glassdoor survey: https://www.glassdoor.com/press/app/uploads/sites/2/2016/04/GD_Survey_GlobalSalaryTransparency-FINAL.pdf and https://www.glassdoor.com/blog/paid-fairly-glassdoor-global-survey-reveals-salary-transparency-perceptions/
– Here’s an HBR article which quite succinctly explains why more transparency is equitable. The problems with transparency stem from inequitable pay, not transparency. If you pay fairly, you won’t have the problems described here (there are some studies, but not conclusive research): https://hbr.org/2016/09/the-case-against-pay-transparency
– Results from a different survey: https://www.thebalance.com/salary-transparency-1287067
– Minor point but, it improves clicks in job postings: https://stackoverflow.blog/2016/07/27/salary-transparency/
– Payscale study: http://fortune.com/2015/10/15/pay-transparency/

I’d be interested to see if you could find any real evidence that transparency itself makes people unhappy.

I have had similar conversations with managers and HR folks at jobs around performance-based bonuses or raises. There is, quite simply, not a single shred of evidence that they improve performance, and plenty to the opposite. But it hasn’t stopped folks from still implementing it. You can keep pushing it as far as you feel comfortable- at some point, they may feel antagonized.

And before you get too frustrated with stubbornness in the face of clear evidence, remember that folks still buy plenty of homeopathic items.