It has been my experience that when working at a company, even if you didn't know or care about the industry/field that company does business in before starting there, you can't help but learn the ins and outs of that field or industry while working there, to at least a partial degree. The particulars of that field will necessarily influence business operations, and therefore, what you do in that company in some form or another. How much one absorbs, and how much he is aware of this will depend on both the individual and the duties of his position, and whether this comes from deliberate training or cultural osmosis. But I don't think that a person could remain completely ignorant of the particulars of an industry after being employed by a company in that space.
That's my theory, anyway. Watch Patrick prove me wrong by describing how he came into knowledge of Regulation E by some other path than training or cultural osmosis while working at Stripe