Because there are actually interesting, reasonable arguements for non-transparency about pay-
some are pathological but somewhat amorale- you can 'get ahead' as a business by paying some people less than market rates, and often if people arn't assertive or are creatures of conform, they might not leave even if you dont give them a raise. (*PS not a fan of this, but this is literally the reasoning in HR)
some could be argued to be generative- Also, not all PI candidates are equal-
• When I started my first jr job, if they had put a posting up for 110-120k like some companies, I would be applying against candidates who would wildly outcalibre me. It's actually better that my company had lower ball salary numbers that they kept a bit hidden because it made me getting into this industry accessible.
• Also on my team though, we've had PI candidates come in that we've hired who ARE worth 120k. They dont have Devops Exp, so technically they'd be an associate, but they might have 4-5 years of exp thats related and transferable.
• If on the add we put '75-130k' for an associate, every individual coming in will aggressively negotiate for 130
• So some obfuscation of the range makes some sense.
• Also there are PI's who outproduce PIIs or PIII's, so having all PI's be paid equally doesnt always make sense.