RPV controllers is not the only branch where the USAF recruits off the street, so to speak. The same has been true for AWACS crews.
The RAF OTOH used displaced aircrew and bunker rats. Before you could fly as a controller you have to qualify in the UKADGE first. The reason why we take people from exisiting roles such as aircrew and GE and re-role them is, I suspect, because the gene pool is too small.
The FAA might be considered an example where essentially they had only FJ and RW.