Nobody ever talks about the other variances.
Different gauges, different temp sensors, different sensor locations, different exhausts, different intercoolers.

Just like fuel consumption, one car gets 10's while other get 16-18's doing the same driving.
Are higher readings more or less accurate than the lower readings. We actually don't know, we all assume what were seeing is correct.

When on the dyno, do they get/see EGT's to confirm what our gauges are actually showing us.