In a case like this, I think they’re mainly worried that the dominance of [insert company] from [insert country] is getting too big.
The huge difference between FTC and EC in terms of the mandate of their operation. Whereas the Sherman Law and FTC are operating with aim to protect customers’ rights or something like that, EC anti-monopoly law is oriented just on that: fighting anti-competitive behaviour. The problem is IMHO that “customer rights” is so flexible term, that (with good support in the campaign contributions, I am sure) it is easy to persuade FTC that almost anything you do is perfectly nice. EC’s anti-monopoly mandate is on the other hand rather strict and inflexible.
EU does seem to be on the forefront when it comes to user rights. It’s always nice to see them not just grazing over the issues