Probably because your "traditional RAF terms" aren't always very descriptive of what the job is now? Times and jobs change, BEagle. Traditions are great, but the forces also have to move with the times.
Your translation of the perfectly fair descriptor "Computer Technician" as "Ground Radio Techie" sums up your loss of contact with what some of the the trades of today actually do. The advanced networked systems of 2014 don't need "Ground Radio Techies", they need computer network specialists. Just an example.