That is an analogy that has been said many times using the "insert trade here" function to fit a persons work/job situation.
There are truths in your(mothers) story but it leaves a lot out. It could be true that the tech did the physical, hands on work. But until someone explained the what and how, the tech had nothing to do (really did not know jack because there was nothing to know). Typically the customer generates the 'what', the engineer develops the 'how', and the tech is the facilitator. One of the best synergies between techs and engineers is working together to create/build a solution more efficiently.
So I am not sure how that analogy applies to a MA environment where everyone is there to learn.
The differences in applied belt levels between style/school that
@JR 137 mentioned will always be there. It is simply differences within the styles and how they progress though the belts. To me, when it stands out is when you see obvious differences in students of the same style/organization but from different schools. I have seen it many times and would say I have never felt it is a curriculum issue but a training/trainer/student issue.
Two instructors can teach the exact same curriculum and a high percentage of the time one instructors students will be 'better' than the other on average.