Yes, I'd expect any car guy to be able to change your tires. Or change your oil. But even resetting the oil-change alarm or tire-pressure sensor can be a hurdle here:
Manufacturers also use skill issues to their advantage to bind tradespeople. Modern cars do need manufacturer-specific diagnostic devices that used to be unobtainable for independent shops. Since that practice has been largely forbidden by the authorities, now the software, cabling, and diagnostic output are made intentionally hard to understand without having taken the corresponding lessons that the manufacturer provides for a modest fee.
If a seasoned mechanic is unable to figure out how to reset the Maintenance Reminder or look up how to sync Tire Pressure sensors, run away.
In the same way that one can use knowledge of one programming language as a means to leapfrog into other languages, other skilled trades are similar. Perhaps there's something that could be said about an ICE mechanic trying to dabble on Electric but that's not the point you're making. So yeah. I know you're trying to make a point about lock in, but when I think of people I want to hire for tasks who might say "Oh, sorry, you have a Volkswagen and I only know how to work on GMC" I wouldn't take my GMC to them either. It shows a fundamental lack of skill in that they don't understand the broader concepts and their universal applications. If I, a programmer, can figure out my Volkswagen, my GMC, my Mazda, my Nissan, certainly a mechanic can. If my appliance repair specialist can only do Whirlpool when I ask for help on a Bosch that's red flags.
One might specialize. Sure. But to refuse? Weird. But I fear I might be getting lost in the weeds here because its all about the approach. "Sorry, too busy to take on work on things that aren't my specialty": yep, understood. "Sorry, I don't know <model> I only know <other model>" bad.
It is not impossible but if you try to go to a random shop you found on Google and fix your Citroen or Renault you might be surprised.
I guess some mechanics will prefer to work with a smaller number of models, because they're much faster if they're familiar with the model, but new models come out every year, and they need to learn how to fix those. If a mechanic can learn to fix the newest VW, they can learn to fix the newest Renault, it just might not be worth their time if they have enough work to do.
I believe person learning GA could learn any other analytics tool. It is just not worth their time.
Any mechanic can fix a Citroen, but is it worth the floor time it'd take to get the parts and figure out french quirks vs working on something they know that they'd make the same money in a third the time.
Having done shade tree work on various cars, I'd totally turn down any Subaru engine bay work if I was already close to swamped.
Most specialty equipment costs less than a mechanic can earn in a day. You even order the parts from the same company no matter if the bumper is for a Mazda, VW, or an Alfa. Or a Kawasaki motorcycle for that matter. This lock-in behavior is, luckily, mostly illegal.
In the US, for a very long time, you had to find an "import specialist" mechanic, even long past the point where Japanese brands had gone mainstream. Part of this might have been because of the availability of metric tools at the time; my family had a set of metric wrenches specifically because they had to do occasional light maintenance on their early Datsuns and Toyotas.
I can recall that the mechanic in my neighbourhood was decidedly unwilling to service a new Hyundai in the late '90s. He complained they were 'disposable'.
Specialized items require specialized tools. Specialized tools, like all other tools, require maintenance and they change.
A shop dealing with domestic produced automobiles can significantly reduce profit-bleed by not servicing vehicles that require special tools, special diagnostics, special machines, etc.
It's simply a math equation. Do I serve enough of these vehicles daily/quarterly/yearly to make these expenditures profitable for me? The shops you're referring to answered no to that question.
Not because of skill issues, but maybe forced because they work for a dealership that sells a particular make exclusively or, less often, a specialty shop; most “car repair guys” outside of those environments have to be generalists.
> Your home appliance guy will preferrably sell and repair one brand of washing machine, dryer, dishwasher.
IME, the sales are done by shops that carry many brands, and delivery, installation, repair donw by firms that often have relations with the retailers and handle whatever you get from them, including multiple unita of different brands that come together with the same team. They may also have relations with the manufacturers, but those don’t seem usually to be exclusive.