It's not really an adjustment though? Amazon's publishing contract has always preserved the standard AND extended publisher rights (which other publishers do the same way btw, maybe not with this level of hostility as they can't afford to lose writers, but publishers have had an insane amount of leverage for decades now).

Basically the moment you agree for Amazon to publish your book, you give them permission to handle it as if it were their own product - you're "just" the author, who gets a pittance from sales.

So unless the authors can show that Amazon's approach is causing them direct financial harm and therefore the publishing contract is to be terminated, courts won't be too helpful.