I don't claim to have any of the answers, and it is a really hard problem. I'm just pointing out that it doesn't mathematically make sense to claim that everyone can be underpaid relative to each other^, and that the claim that software engineers are underpaid in general relative to the value they create is a separate issue.
^ That's like saying that two people can each be shorter than each other. It's not possible according to the way the "less than" function is defined.