It was always my personal belief that the JPA claims system was so convoluted and time consuming that for small claims many (most?) people couldn't be bothered to claim that to which they were entitled to under the rules pertaining at the time.
Long before then Biggus, particularly with the use of private cars for dashes around the base and locally. I remember being told in the late 60's that the Service would collapse if we merely played by the rules and insisted on MT providing direct support to day-to-day personnel movement in support of ops around a station and its environs. Can you imagine it....
"MT I need a car and driver now to take me from SHQ to the Bunker" "MT I need a car and driver now to take me from the Bunker out around the perimeter to the Squadron. " MT I now need a car and driver to take me back from the Squadron to the Officers' Mess for a Summer Ball Committee meeting"' etc. etc. and multiplied by dozens of others a day going about their business in support of the Crown. ( Yes, I did have MT vehicles later allocated for my own use, the first of which ( sort of) was a "sit up and beg" bicycle from the SWO's stores ).