Boy, aren't we all glad the DOJ protected poor little Amazon from the evil and all-powerful Apple e-book conspiracy and monopoly.
I'll reserve judgement on whether Amazon's conduct is legal or not. But, Apple's collusion was decidedly illegal.
In any case if the DoJ feels that Amazon is misusing monopoly power, then the solution is to prosecute both and not, it'll all cancel out in the long run.
In the e-book conspiracy, all the publishers wanted better terms than Amazon would give, and they didn't want to give Amazon the chance to play hardball, so they banded together and forced Amazon's hand.
Not really sure how the second is better. It's certainly way more illegal.