> I'm confused how this is a monopoly
An example from the case would be: Google bought Admeld. Then it disabled it's real time bidding feature. This created short term losses for them but gave them long term advantage in market control.
> Even if they play games with the auctions to keep the price up
Then it should be noticed, competitors should form, and the market should move away from this provider. Yet this has not happened because Google keeps buying those competitors.
> and it's not as if anyone is forced to use them.
Technically? Yes. Practically? No.
> that the app store isn't a monopoly, but Google ads are.
Our federal courts are separated into districts. Not all of them use the same precedents and market logic when deciding cases. This is probably why congress passed a law that prevents large companies from removing cases to the district of their choice and instead forces them to hold the case where the prosecutor decides.
The latter point is one reason why this case ended up differently.
> There's other ad companies
Loss leading, exclusive contracts, and price fixing are all crimes that can be committed in that environment. The bar for anti trust isn't "100% market domination." It's actually pretty nuanced. That's a good thing.