i think its a thing where the GM dealer replaces the entire engine (which is not that common), and the car isnt running properly then they can hook up the Tech 2 and see what is going on......

GM techs also have more resources to consult and they also have TECHline that is online support AND phone support.....

Understand that there are many levels of GM and ASE traning....it Takes MANY years to be come a GM/ASE Master Tech

the Techs may not have been taught about the Case Learn in there training yet or just dont use it because they dont need to.......

Probably been discussed before but this is sort of interesting (in reference to the intense PCM):
"Please note that 1997 model year vehicles DO NOT require a CASE Learn if the knock module (square cover attached to the PCM with two allen head screws) is simply swapped over from the old PCM hardware to the INTENSE™ PCM hardware."