I think that as the automotive industry evolves to EVs, and I truly believe that in 20 (or 30, accepting that many by-then old cars will still be on the road) years the new car offerings will be either EVs or hybrids with a very small percentage being gas only, the knowledge required will be very different. Old time “grease monkeys” who learned hands-on only, (for whom I have only the utmost respect) will become largely obsolete. There will still be steering systems, suspension systems, and braking systems, but even they are becoming more technology-driven with the passing years. Training will be even more intensive, and may even evolve to fill four year degrees.
That won’t alter the “mechanics who shout” proportion much of at all. A portion of every population consists of people with little culture. Or perhaps “control” is a better word. I recall the term “going postal”, but in truth the only reason there seemed to be so many in the postal service losing control was IMHO because there were simply so many people working for the postal service. The media made it sound like a postal problem, but I suspect there were proportionally just as many people “going postal” in most other fields of endeavor.