Google is not presenting their own competing services in a biased way over others. They are presenting search results in context sensitive ways. Searching for sushi in a geographic location indicates you want to find sushi places in that area. A google map is the best possible way for google to present the information you want. Does a crowdsourced site completely dedicated to this tiny niche do a better job than google's algorithm? of course it does, but there is no way for google's algorithm to judge that for every query.

Search instead for "sushi review stockholm" and the cited website is the first result and there is no google map at the top, because the search does not indicate to google that the first priority is to simply find sushi places and nothing else.

Now if google was artificially placing gmail, or google docs, or any of their other service products that are not themselves presenting search results, above the competition for generic search terms; that would be a problem. The behaviour cited in the post is simply the best way for google to provide search results. Google maps is a core search technology, just like google image search, books, video etc. You can't use anti-monopoly rules to handicap the dominant product itself. Especially when all the competition (search providers) considers the same behaviour to be part of their core search service as well.