It's pretty obvious that Google et al. do a lot of "custom" filtering like prioritising Wikipedia, removing porn from "obviously non-porn" searches etc. (That "Berlin" search gives porn as the 8th result.)
I doubt that Google prioritizes Wikipedia deliberately. Wikipedia has tons of backlinks, authority, trust, typically a high text to html ratio, probably a low bounce rate. Moreover, it is fast, works well on mobile and on and on. It's is just a very well done and useful site for users and search engines.