I certainly expect my mechanic to tell me he’s going to install non stock/genuine parts beforehand if some happen to need replacement. "Hey, your brake discs/tranny/whatevs is dead, let me swap that for some (possibly non spec-compliant) third-party part! You'll save xx bucks! (and hopefully it won't break down in YY000km at the most critical moment, nor fuck up the whole thing because they're not properly balanced or whatever! but shhhh I'd rather not tell you that)"

I can't think of a single time a mechanic or shop has given any details about the manufacturer of a part, just "do you want the expensive shit or the cheap shit". Of course in the auto parts world virtually everything is aftermarket not OEM and there isn't a monopolistic manufacturer trying to enforce their bullshit on repair shops.