> The end result is a company giving pay transparency ends up either with a much bigger labor bill, or staffed by poor performers.

I think that a system based on secrecy and/or asymmetry of information won't last long, and in fact I think the current "chaos" happening in the labor market suggests that a majority caught on to what their "true" market value is despite salary secrecy and companies will have to deal with a bigger labor bill no matter what.