Amazon does not collect more data than Google does, even by your own definition. In fact, Google uses Amazon to collect even more information than they do innately by mining Gmail for purchase receipts.
Amazon purchases your credit card purchase history from major CC providers, likely as part of reciprocity agreement. They know more about you thank you think.
Source: I was retargeted on Amazon for an impulse buy of an obscure item from Macy's. My CC was the only way to join my data.
