Here’s Matthew Yglesias explaining why many Senators are not experts on public policy:
Senators and members of congress have extremely time-consuming jobs, and the job is basically to fundraise, to travel a lot, and to hustle on behalf of the interests of donors and parochial local interests.
This is one of those everyday economics lessons that I think comes in handy in many phases of life. I used to work fairly regularly with people who were consultants for enterprise software companies. What I soon realized was that the core competency for these people was not software development skills or even product expertise but rather willingness to travel. Most of them just showed up and then spent most of their time asking people in the same office questions we could have asked them.