This just came to mind when you mentioned "ad tax". Google Adsense recommends you stuff as many ads on to your page as possible. They even alert tell you when

This just came to mind when you mentioned "ad tax". Google Adsense recommends you stuff as many ads on to your page as possible. They even alert tell you when you are missing out on revenue by not including the maximum number of ad units. At the same time Google Search announces a penalty for overly ad heavy sites. Ultimately, I believe most of Google's "search penalties" actually serve the purpose of driving any site that makes money to paid search. They disguise them as "UX enhancements" but they really just want you to pay for traffic. They are even trying to compete with Amazon in the Google Shopping product.