[kalleboo]

Maybe they mostly go after American companies because mostly American companies are in violation?

And it's not as if EU companies go without scrutiny. Due to the still-fractured market, most are small enough so their antitrust matters are localized to one country, but if you check the EU website there are still plenty of cases, they're just not sexy enough to make the news - like the a recent case "Commission fines maritime car carriers and car parts suppliers a total of €546 million".

In for instance the "state aid" tax preference cases cited in your link, the EU has also launched investivations into European companies like IKEA and Fiat cars.