https://support.google.com/google-ads/answer/142918?hl=en
https://support.google.com/google-ads/answer/6366577?hl=en
The mechanism of the auction is opaque.
Reasons:
- Quality scores which are not public.
- Quality scores change with every query.
- Locations of users and their personal preferences are taken into consideration.
- Self-learning artificial intelligence is applied.
Only some general principles are disclosed to us.