I'm curious to know why a lot of car reviewers, when they are reviewing a VW or Audi, always describe the Audi as though it's just a VW with an expensive badge. This is far from the truth. Firstly, Audi AG is still a separate corporation. Since VW acquired Auto Union back in 1966 and bought back the Audi name, it has had its own independent engineering and development division. Audi developed the Audi 80 and 50 which VW adopted and renamed Passat and Polo respectively in the late 60s and also developed the original Golf for VW because the Beetle sales were going down. You can look at it both ways regarding the cars that share underpinnings but I would certainly buy another Audi, not just because of the four rings but because they are engineered, developed and built by Audi AG and they have the heritage behind them and they are just a very well-built car. Maybe some reviewer might give Audi a little more credit than just being a rebadged VW.
Historically you are correct but the current situation is that Audi mostly uses “tool boxes" of platforms and parts developed by parent company Volkswagen. It dresses them up nicely and adds quality but it's still a fact that an Audi A1 is a VW Polo under the skin and that an A3 is a Golf.