It's hard to tell what the distribution of income is without good data. I'm skeptical that normal, non-startup businesses fall into this pattern. I'd expect more of a log-normal for most industries.

The log-normal also applies somewhat for lawyers. The partners of big firms make millions annually.

As long as we're getting into nuance, I should add that the two-peak distribution is most clear for lawyer starting salary, not long-time professional. You either go top firm or not.