I never said members of Congress know which rules are being implemented, but the leadership of the agencies do, which are appointed by the President and confirmed by the Senate. If Congress was unhappy with a rule the agency has passed, they'll repeal or amend the statute.
They have to know what the rules and regs are in order to know what needs to be repealed. They have to care about things like that. But most don't. They just trust that the noble sounding titles keep the gullible people appeased and assured that their government is wonderful and is doing wonderful things for them. What is actually happening isn't really important.