The EU anti-cartel unit regularly takes on big EU multi-nationals.
This is as silly as saying that the United States only acted against Volkswagen in the diesel scandal because they were not American.
I've seen the EU in a club in Brussels blowing all the money that they took from Google and the British couple on booze and women.
Joking aside, I'm fascinated by the narrative by HN user on the EU.
However, the article points out perfectly well how Google uses their de-facto monopoly on Web search to stifle competition in other areas (such as specialized search services).
The couple can sue Google for damages as soon as its violation of anti-monopoly regulations has been established. They just need to wait until Googles appeal against the decision is rejected (which it most certainly will).
So I would think the biggest cost would be time and energy and that is enough to put the majority of people off. (One of the first things I heard from a lecturer as part of my law degree was: never, under any circumstances, go to court, unless you really, really have to, as it is not worth your time and energy.)