Well, if the FAA is still using vacuum-tube electronics, I guess they're also using magnetic compasses.
On the other hand, maybe they just assume pilots are too dumb or too ill-informed to know about correcting for magnetic deviation -- in spite of the fact that magnetic deviation is one of the first thing anybody learns when undergoing basic training for map reading, surveying or navigation!
Maybe it’s so the pilots have one less thing to correct for.
As an electrical engineer with my specialty being RF, who is also a pilot, this is something that crosses my mind every time I enter controlled airspace.....