Lexus/Genesis vs German Luxury... what does 'better build and mechanical quality' actually mean?

I repeatedly hear the statement "Lexuses and Genesises just have better build quality than German counterparts these days".

But when I watch in-depth mechanical and interior build quality reviews and listen to reviewers defend this statement, the only factors they end up actually mentioning are: - 'Lexus/Genesis parts are cheaper because they're the same parts as Toyotas, Hyundais and Kias'. - 'the mechanical parts of the car are simple and easy to repair'. - 'there's more parts going around'.

German cars are simultaneously 'overengineered/complex', and 'worse in mechanical and build quality than Japanese/Korean luxury counterparts.'

I used to think that build quality refered to the amount of finesse and performance a form provided. For example having unbreakable material choices in a mechanical form that provided power and smoothness.

But, rarely, if ever, do I hear about what it is about the Lexus/Genesis engine's technical and material composition that apparently makes them have 'better mechanical and build quality'.

Do I just have the idea of 'quality' wrong in my head when it comes to cars? How can a Toyota Klug ever have better mechanical... and build quality... than an Audi Q7?