The benign and simplest explanation for all of this is that Apple has painted itself into a corner, that it hasn’t really thought through all these issues. And if that’s the case, something will have to give: a bulk-submission tool, lax review of products, or (ideally) an abandonment of the new rent-seeking policy.
Right now, even if Amazon wanted to give Apple 30%, it would have to manually enter each Kindle book into the iTunes Connect Web site and submit a screenshot showing it loaded into the Kindle app. Then wait for Apple to approve it. And this assumes that Apple will raise the limit for the number of SKUs that they support; if they don’t, it would not even be possible to make the Kindle app comply with the new guidelines.