Why does he need a license in Afghanistan or where ever he is positioned?
Irrelevant of where the forces are deployed, to drive a military vehicle, we have to be in possession of the relevant class of driving licence, be at B, C, H etc, , also we have to take a further "matrix" driver theory test periodically. As well as this we have to undertake a training course for each variant of vehicle that we will drive. in the case of this guy, he is a mechanic for the EOD teams so he will very likely be qualified to drive a massive variety of vehicles ranging from landrovers, through to HGV/trailers, tanks etc.
if we are to go away to any other nation with different driving laws such as germany/canada/middle east we have to undertake further training before leaving and whilst there to ensure everyone is upto speed and fmiliar with the new road systems/laws etc.
just for the record im not trying to justify his case, merely explaining why he would need his licence overseas