Also any offline store where you pay for something with a credit card. For me the convenience of not having to deal with cash on a daily basis is worth it. I can see how others would take a different viewpoint, but one really has to be cash-only if they want to avoid their financial habits being data-mined.
Yep, if you buy something from walmart.com with a credit card and later go to a physical walmart and buy something else with that same credit card then that item you bought in store will show up on your walmart.com account.
This happens at any online store you purchase something at. This isn't unique to Amazon.