Well if I search "height eiffel tower" on Google I see the 'one box' but I don't see any ads. At least in this case Google seems to be placing user experience over (short term) bottom line.
Good example. You won't click the top organic link (Wikipedia) because the answer is right there, and you'll miss the pop down banner ad from Wikipedia where they are asking for donations. Just below it, you see a bunch of questions related to the Eiffel tower that generally jump to ad filled pages, but only pages where the ads come from Google. And on the right you'll see a link to Google maps for the Eiffel tower where, if you click on the map link, you can find places that advertise on Google where you can eat or visit and some reviews of them, if you click on the Eiffel tower link you'll go to a web site that sets up tours. (and pays Google to be there)
What you won't see are any Yelp recommendations or links for the Eiffel tour (you would if you searched 'height eiffel tower yelp' and got https://www.yelp.com/biz/la-tour-eiffel-paris-4 as the first link).
Google has effectively wrapped your 'factoid' type search with pretty much any sort of commercial intent query you might have, around their content, so that if you were a restaurant you would much rather have a lot of Google reviews because you would rank higher in that map link, and if you were a tour operator you would want to bid on the link under the 'keyword'. And if you were a content site you would want to have your links up at the top of the page under likely queries you may not have thought of yet, but once you read them you go "There are two? Really? Lets check that out."
Having operated a web search engine and seeing all the ways the product guys and gals could, and did, "tweak" things I look at that sort of page much more critically than the typical user.
