Restricting them too much is a double edged sword because a lot of people use government work as a stepping stone even if they don't go to work for people they directly deal with. Making it too hard to find a job after can make good lawyers never go into public service because they couldn't get the cushy private gig afterwards.

Politicians don't have much incentive to do this since plenty of them get cushy jobs at bigco benefactors of the spending bills they voted on. Trying to target prosecutors would cast a eye on themselves.

It's like trying to separate church and state in England back in 1600-1700s.

"Politicians don't have much incentive to do this since plenty of them get cushy jobs at bigco benefactors of the spending bills they voted on."

It is the same problem - bribery/corruption but hard to proof and not much interest to investigate.

Then some friend of Boeing CEO would invest in prosecutor's startup

Or firms could trade hires ("if you hire this person, I'll refer a client to you"). Or they could "persuade" a client's legal dept to hire her ("We're looking for a new partner and we like your experience... On a totally unrelated note, I know a talented young woman who's looking for a job...")

The allegation is the prosecutor got a cushy gig at the law firm, not that they subsequently worked on the case after switching sides.

Ah so the implication is not that the prosecutor gave them inside info on the government's case's weaknesses but the prosecutor intentionally played the case suboptimally in hopes of being paid after the fact? If this was done with prior assurance that sounds already illegal no? If it was done simply on the hopes of securing "payment" afterwards with no prior deal then that seems like a large risk for the prosecutor to take.