I think you'd make a very hard time making that stick (and a field like software development, where the 10x more productive programmer is generally believed to be a real thing, would be particularly hard). There is no reason why a company operating in good faith should want to deter exceptional candidates from applying to a position, and exceptional candidates are both much rarer than "slightly-above average" or "underqualified but trainable" candidates and able to command much higher salaries.

But the possibility otherwise satisfied employees being paid a market wage commensurate with their experience might see ads for jobs similar to theirs and conclude they're being systematically underpaid and motivated to take legal action is definitely a negative second order effect of the law...