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.