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.
Great points all around! The reason I think small businesses are relevant is that the founders/owners own the entire business. They either lose money, break even, or make money. In the sucessful small business cases where they make money, since they own 100% their profit requirements for a good return are far lower than those of a startup. I'd guess it's still a power law scenario (just with less amplitude than startups).
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.