They are the experts, but I have to wonder about the health of Amazon's main business of a few years ago.
They used to be the low-cost supplier of physical books, and had good prices on many consumer goods. Combined with free shipping over a low threshold and avoiding tax, they were a really good choice of price-aware consumers .
I seem to have figured this out just a little too late. Over the past two years much of the advantage has gone away.
I joined Amazon Prime just before they started charging tax and switching items to the new "Add On" category where free shipping doesn't apply. Items that are still available with Prime shipping have been marked up, often well over retail, to include shipping cost.
Subscribe & Save is another part of the Amazon shopping that is becoming annoying rather than helpful. It's pretty much rolling the dice with prices. In exchange for saving 5% (sometimes 15% or 20%), it means you agree to whatever price they pick on the day they ship. I've had prices more than double between shipments, with no notice. Things that still have an especially good price are frequently "out of stock" -- I just had my entire April shipment canceled because of this, But other times they don't hesitate to consider a smaller package as the same product.
Bottom line is that I see Amazon has an amazing, broad business. But the consumer-facing part is inconsistent and unpredictable. The result is that there is a lot less brand loyalty there than with most businesses, and that could result in a crisis with any misstep.