Why do gliding clubs have airfield frequencies if they never bother manning them? I spent a summer gliding at one club, and was amazed at the attitude to the radio; they hardly seemed to know it existed. With a lot of other airfields around the location, and plenty of passing traffic, it seems to me simple courtesy to put in the small effort of using a radio.
After all, you can't complain that powered pilots aren't safe enough with one breath while blustering about not needing the added safety of radios with the next.