Because the financial incentives don't reward it[1]. The only way you'll get what you're describing is via government regulation. [1]: There's actually a much

Because the financial incentives don't reward it[1]. The only way you'll get what you're describing is via government regulation. [1]: There's actually a much much longer-winded answer that gets into the complexities of advertising across hundreds of millions of small publishers that is too much to cover here. Honestly, you could probably write a book about the topic (and odds are someone already has).