With regards to teachers or photographers, that's not a fair comparison in my opinion: in those cases, low wages are mostly dictated by high supply vs low demand, so from an economic point of view it "makes sense". That's much different than software engineering or medicine, where there is a scarcity of supply (and the only reason why software salaries are in the 6 figures).

In other words, teachers are not willingly giving up a portion of the compensation that they could otherwise be making doing the same job somewhere else. In software instead, that happens ("Oh, you work on FOO v2.0, I'll happily take 40% less than what I could otherwise be making doing this job in another company").

I don't know about public defenders, you might have a point there.