When I had my ‘73 BMW 3.0cs, I would drive to the dealership to buy parts (this is back when Mobile Traditions was a thing for BMW and they kept deep stock of parts for their vintage cars- it was (note the emphasis on the past tense) a point of pride for them.
One day when I came out, several young mechanics were standing around my car. They asked me to pop the hood (the fact that it opened backwards was a marvel to them) and one pointed at the dual Weber carbs and said “what’s that?”.
Just because they are “authorized” to work on something doesn’t mean they know how to handle it. That said, my independent mechanic specializes in vintage BMW’s and he has a staff of 3-4 guys ranging in age from 30-50, all know how to tune carbs by ear, all know how to use feeler gauges, all know how to trouble shoot a vacuum leak without a computer and all of them know to keep parts removed from a car until the customer is shown the parts upon pickup and signs off.