Maybe it's not so bad for the employer in the long term if it leads them to realize "Hey, we need to do better about assessing the value of our employees."

I'm curious what the data point is that leads you to think your company's paying a good salary if the hard-working, motivated, skilled people can easily find work that pays quadruple, because that sounds like the market is saying otherwise (unless the missing variable is location, like moving from Nebraska to Silicon Valley or something).