I think you are only looking at the most obvious at the expense of everything else. Ig google is my go to place for news, I would also use them to search for either news related or unrelated terms. If all news sites were unlisted from Google but remained on Bing, Bing's search revenue would increase and Google's will decrease.
I don't know who makes more money out of the relationship, that is not the problem here. Even if news sites make more moneyz they did not sign a contract with Google accepting this financial relationship. If google treats any sites in a special way to increase their own popularity or brand value, even if that site is already benefiting from the relationship Google must either get all the sites consent or negotiate payment.
If a person goes to a news site, the news site makes more moneu but that's a big if. The special treatment means people will glance at headlines and outlines extracted from the news sites and only click on a few sites. This special treatment means less ad clicks for news sites as compared to normal google listings