Well interesting thing here the standard Fiesta has 1.5 negative camber stock. Ford took out some of the negative camber in our cars by installing a stiffer twist beam with less camber so the car would oversteer more in the rear. Now we all are adding more camber in the rear to increase corner grip but technically that induces more understeer upfront which I can personally attest after initially installing my camber plates during the testing phase. I found I had more grip in the rear and could enter faster with a much higher breakway at the expense of some understeer upfront. which one has to compensate for with suspension tweaks upfront i.e stiffen the front more etc.. . I added a rear swaybar to see how that would do and found it induced less understeer but more sudden breakaway . Not sure if its gonna stay on at this point will be doing some more testing shortly for that decision.
I digressed though. Perhaps his car was in an accident and someone put a stock Fiesta twist beam in rather than a ST? Our stock rear camber range is from–.3 to -.8 alignment spec wise. The only other way is they installed washer shims that some alignment shops stock for that kinda of thing.
I can only speculate the other thing might be there equipment was out of spec and the readings were off.