I think the use of the term representing the side of a vehicle is pretty common world wide, but the Americans of course have to, by habit, change one or two words so the one we hear on our Americanised TV is usually "kerbside" rather than "near side".
In the case of vehicles, left and right is not always that simple. I remember going to a windscreen manufacturing business way back when we had coaches to get a new near side front windscreen manufactured and fitted. There was much discussion as to which screen was to be done so eventually the fitter, who was inside the coach with me, decided that what I was describing as the near side was in this case the left hand side, so that is what he wrote on the order sheet. Once this "one off" windscreen had been manufactured and was to be fitted it was discovered that it wouldn't fit. ($1100.00 down the drain plus more down time for the vehicle) so the actual manufacture leading hand came out, stood in front of the vehicle, pointed to the drivers side of the coach, which was to his left, and stated "That is the left side screen and that is what I made." Had the term "near side" been used there could not have been any confusion whatsoever..... similar to Port and Starboard on a ship.
As to the two photographs, I am currently in contact with one of the OCs of 26 Coy but unfortunately that photo (F1s) is after his time so he is making further enquiries amongst some of his fellow Officers so hopefully he may come up with an answer sooner or later. (I know that the top ones are right cause I did the 87 ones!!![2nd and 3rd trucks])
As far as I know SOVOS and VOIs both state the same position so I am assuming that the "wrong sidedness" may be a particular understanding by one particular person of the word "near side" as in Vietnam traffic is left hand drive and drives on the opposite side of the road to us.
On an aside, it is quite interesting to see those tippers wearing the 26/522 Tac sign as the 26 represents the Coy number and the lower 522 depicts a GS Company
Regards
Glen