Back when Amazon started, they killed off the brick and mortar competition because people would visit a bookstore, pick out a book, and then order it on Amazon. Back then Amazon did not collect sales tax, so it was cheaper to ship a book from Amazon then to buy it in a local store.
Now the same thing can be done to Amazon. They have built an enormous, easy to search, and expensive marketplace for just about anything you could ever buy. After searching for items on Amazon's site, you can now give Amazon some payback karma by purchasing the items from the manufacturer's site often for less money as you avoid the hefty fees to access Amazon's marketplace.
Since Amazon deplatformed Parler, I have personally saved $250 by simply searching for items on Amazon and then buying them from the manufacturer's online store. All it cost me was a few days extra shipping and a few minutes of time.
That is another thing that annoyed me about Amazon. Before they became large, they were against the state sales taxes, but then after they became large they became for them, because they didn't want competitors to do the same thing they had done.