In my view, there's no hard and fast answer because there's a sliding scale of quality. As you go from the cheapest bikes, up into fairly expensive ones, there's a progression of slightly better materials, manufacturing quality, components, and so forth. Back in my day, you could see it in the number of aluminum parts on the bike, versus steel. Today, the name brands have their own progression of quality, so a brand name on a bike part means relatively little unless you research that brand. On the other hand, I suspect that a company like Shimano makes an effort to provide decent quality on their cheapest parts. I've never seen a Shimano part that was outright bad, and I have scratched my head over exactly what makes the more expensive ones nicer, other than aesthetics.
I've worked on a lot of bikes, including "department store" as we used to call them. Every bike needs to be adjusted into functional operation. Nicer bikes are easier to adjust, and hold their adjustment for longer, because things like screw threads and mating surfaces are formed more precisely. You can teach someone how to maintain wheel bearings on a nice bike, because it will feel a certain way when it's right, and any damage to the bearing surface is a sign of a bad bearing. On a cheap bike, it's always a judgment call when you're done, because there's no sweet spot between feeling loose and feeling crunchy. With experience you can make a pretty good guess as to what's good enough, and the rider will get plenty of service out of the bike, but it does take experience.
From what I've read, every bike needs wheel service, right out of the box, to make up for under-tensioned spokes resulting from the automatic wheel building machines. This has to be done by you, or by a shop.