Antitrust law is weird, so I can't comment on this definitively. That said, in the EU-Adwords case, the focus was on "abuses," primarily in the contract with se

Antitrust law is weird, so I can't comment on this definitively. That said, in the EU-Adwords case, the focus was on "abuses," primarily in the contract with search partners. Adwords is their buyer, rather than seller. Technically, Google is the monopoly, adwords is the monopsony. In any case, prosecutors needed to prove harm/abuse affected search partners, and the fine was presumably based around that. There is a problem defining the market sometimes, but that wasn't a problem here. It's a "crack for economists" type of problem, with a lot more theory than needed for practical purposes. The problem is/was that these courts aren't a tool that can do the job. Courts can keep monopolies from doing certain things, with varying degrees of effectiveness. They can't prevent a monopoly from being a monopoly.