The thing is, police and politicians don't care about getting correct results, they only care about results. An innocent person convicted is still "case closed" and "another criminal punished."
Politicians can be made to care by threatening their jobs, but the police still don't give a shit about catching the right person as long as they can put somebody behind bars by any means possible.
I'm their view, the experts are part of the problem and should be ignored.
You misunderstand. A librarian may not know if something is true or not, but they are educated on how to research something to find out if something is true or not. As you said, their job is to manage sources, which includes knowing with sources are reliable and which sources to look at for certain types of information.