To add a little context based on an antitrust course taken in a U.S. law school a few years ago, European antitrust law is quite different from American antitrust law so American ideas about market share and consumer choice may not be applicable.
In the U.S. the primary focus of antitrust enforcement is on the consumer, so if the consumer is getting a solid product for "free" and has lots of other options, there is no chance of an antitrust action happening.
From what I remember, European antitrust enforcement also takes the well-being of competitors into account, so if one company has a large market share and enough pricing power to make it difficult for competitors to survive, the authorities may bring legal action, based on the theory that it's better for society to have more different businesses offering choice and employing people.
I don't think this is actually all that different. Both jurisdictions recognize that competition is preferable. Minor differences in why they focus on that, is probably not all that relevant. Making it impossible for competitors to function in the US is problematic as well, because it leads to a lack of consumer choice. (Just because Google is free, doesn't mean all of us want it.)
Furthermore, the EU has demonstrated overall a stronger focus, I think, on the individual over corporate interests. Seen also in their handling of privacy, where they're willing to place large burdens on corporations in order to adequately protect their citizens' fundamental rights.
In the U.S. the primary focus of antitrust enforcement is on the consumer, so if the consumer is getting a solid product for "free" and has lots of other options, there is no chance of an antitrust action happening.
From what I remember, European antitrust enforcement also takes the well-being of competitors into account, so if one company has a large market share and enough pricing power to make it difficult for competitors to survive, the authorities may bring legal action, based on the theory that it's better for society to have more different businesses offering choice and employing people.