tl/dr: email chains used as evidence in DOJ Google antitrust case show internal arguments about drops in # of searches, and how to increase them so that people see more ads. Search team wants to create better search results to keep people coming back.
Advertising team wants to find any way to make people search for as long and as often as possible (“increasing the journey length”) even if it means delivering less relevant search results.
You can actually read many of the trial documents here -
https://www.justice.gov/atr/us-and-plaintiff-states-v-google-llc-2020-trial-exhibits
this file was particularly interesting. https://www.justice.gov/d9/2023-11/417557.pdf
i personally see them as different tools of the same end goal - wealth generation in a checked and sustainable manner. capitalist environments inspire innovation, but require boundaries set (regulators) and a political environment which is alert and aware of exploitation and can make the calls about what is or is not acceptable.