The issue stems from third-party sellers' goods being commingled with the genuine products in the logistics chain.
Keeping the same products in a single bin, instead of segregating them by source/seller is more efficient, and saves money.
Sellers (those who aren't pushing fakes) can be victimized by this as well, and can choose to keep their stock separate, but it costs them more to rent their own bin.
Marketplace has overtaken Amazon's own sales as the largest part of their retail business. Charging fees to warehouse, deliver, and even discard returned goods is a moneymaker, which is why others, like Walmart and Target, do it as well.
Amazon doesn't sell Milwaukee power tools. Nor Ridgid, not Ryobi. Look more closely at the listings, and note that those products listed on Amazon are from third-party sellers.
TTi has strict control over their retail distribution, and writes their warranty policies with this in mind. Home Depot is of course the largest, with an exclusive on Ridgid power tools, and its LSA coverage only applies to purchases made from HD or DTO, which is TTi's own outlet channel. I don't own any of the other two, but they are probably similar.
As as whole, Amazon stopped "caring" a long time ago, by allowing sponsored and free product reviews, and not fixing the structural faults in its review system. Along with allowing questionable, if not dangerous goods to continue to be sold, even after being outed.
It's far from a place like Aliexpress, but not the safe refuge some assume it that it is either.