Federal law and regulations require insurers to hand over exactly this sort of information in response to a written request. And they have to do it fast: Most people who get insurance through an employer should get the records, called claim files, within 30 days.
There’s just one catch: Some insurers aren’t turning files over like they’re supposed to. We followed ProPublica readers through the process with five different insurers. Several companies only shared documents with patients after we reached out.
My guess is the company wants a lawyer present because they assume that anyone who is requesting this is probably going to bring one as well.
Basically they don't hire people they would authorize to tell you the reason.