For law, it's pretty obvious. There's the partners at white shoe law firms and then there's everyone else--many of whom are doing personal injury law or scraping by doing routine wills, real estate, etc. Sure you have in-house corporate counsel and the like who are somewhere in the middle, but it's not hard to imagine why it's generally bimodal.
With programming/software engineering OTOH, yes you have outsized salaries at some big firms mostly in some high CoL areas, but it's a generally pretty well-paid field even if it does tail down for developers at non-tech companies in low CoL areas.