I don't see why an aerodrome should go to the expense of installing an AFRU for the numbnuts who are too tight to buy or too lazy to read ERSA / NOTAMS / Charts etc. Maybe the aero club could have someone with a hand held on 126.7 listening for recalcitrants doing their inbound calls and politely point out their error.
Having an AFRU on a frequency where it's installation is not published would probably only confuse matters more. Put it in a NOTAM I hear you say. Well if they don't read the other stuff, they probably won't read NOTAMs either.