This was covered in the Steve Ritchie interview.

Bon Scott hasn't been in the band for over 30 years now. It is extremely rude and disrespectful to Brian Johnson, the current band member for the last 32 years, to include Bon Scott. The machine was modeled after the acdc band as it stands for the last 30 years, and that's without Bon.

Again, these are not my words. They are from the game designer. You can look for his interview and listen to it yourself. So theres no point debating the validity of this argument with me. But that's the answer.

And if your game you played had a lower playfield it was either a premium or an LE. The pro has no lower playfield.