I think it's not quite that simple. Individual HR people may not all be critical thinkers, but HR people do salary research and keep up with trends in hiring.

I think it's not quite that simple. Individual HR people may not all be critical thinkers, but HR people do salary research and keep up with trends in hiring. They have their own professional communities where they discuss this stuff. Even if they aren't all individually doing it, some within the HR communities look at such things and talk about it with others. They use this to advise each other and their execs if nothing else. HR industry groups could, as a body, look into whether "the industry standard" is getting hiring results as well as employee churn, satisfaction, and company-reported satisfaction with their hiring outcomes and make that information available to HR people and then to whomever needs to take it into account in strategic decisions.