Cars is just one example, a mechanic of 40/50 years ago, would have had a thorough understanding of them. Now it is near impossible to have a complete understanding, because they are so very complex.
Rare to find a mechanic now.
Mostly, they're fitters.
Probably a combination of lack of skills, training, and interest, and it being uneconomic to dismantle and rebuild a component.
My recovery Co' once sent t'young lad out to roadside a classic Velocette motorcycle. He was attempting to attach his jump pack to 'boost' the starter & not understanding why the owner was furiously beating him away . . . . . .
Job came in for a Mk1 Cortina non-start, bestest mechanic in his 60's jumps up & says "I know exactly what's wrong with that", pops out to fit a new roll pin to the rotor in the distributor cap & it's something he has fond memories of doing 1000's of times all those years ago.
To be fair there isn't much on vehicles these days that can be 'fixed', certainly not roadside.
Rare to find a mechanic now.
Mostly, they're fitters.
Probably a combination of lack of skills, training, and interest, and it being uneconomic to dismantle and rebuild a component.
But there's even more to learn and know about now on vehicles than there was 10, 20 or 30 years ago. It's why there is a tendency towards specialists of certain types or marques.
There are cowboys involved (as there always has been) but don't believe that there's a lack of skills generally
Rare to find a mechanic now.
Mostly, they're fitters.
Probably a combination of lack of skills, training, and interest, and it being uneconomic to dismantle and rebuild a component.
Showing my age now but when I started my apprenticeship, we overhauled practically everything. Engines - rebored and reground, Cylinder heads - decoked, cut valve seats, reface valves, fit new valve guides, starter motors - brushes and bendix gears, flywheel ring gears, dynamo's, gearboxes, steering boxes, propshaft U/J's, leaf spring bushes and shackle pins, rear axles, king pins, bushes and thrust washers etc etc - we even fitted new linings to brake shoes and clutch plates. I haven’t done any of that in the last 30+ years.