You know a lot of this already so it's a general response to the phenomenon rather than your post.
Many audis and vw models are essentially mechanically the same vehicle. That's why you see so many. They use identical parts and materials - more VWs are sold so there are more vw dealers and service places do double duty - so you're seeing a disproportionate number of Audis for that reason in part.
Many models of each vehicle suffer identical service and mechanical issues as a result and the big differences tend to be in unique parts, electrical harnesses (as the vast number of late 90s and early Ought VWs with one sided light clusters can attest) and difficult or complex engine components like Turbos and oil pumps.
Another important factor in car reliability that is overlooked is region - both for assembly /fit/finish problems - as well as local weather conditions (Puerto Rico for example has a maintenance frequency that's often double elsewhere because of salt, heat, humidity and road quality).
And foreign cars are often disproportionately rated as unreliable in "emotional" polling like Consumer Reports, where users equate novelty with difficulty and parts availability with resilience.
The "initial quality" polls on Consumer Reports are sort of laughable as a result because the disproportionately older respondents and methodologies mean that a car with small volume dials gets hammered by credulous Mr Magoos.
I almost bought a VW Phaeton with the W12 Lamborghini derived engine for $10k - which is probably what it would have cost me per month in gasoline and oil changes.
