Ethereum is better for consumers and Amazon.com because....

1. Lower fees. Amazon.com doesnt charge an extra processing fee, but with credit/debit card fees ranging up to 3.5%, they certainly have those fees baked into costs. Since Ethereum is decentralized and doesnt require a bank or government to process transactions, there are no middle man fees. This results in savings for both Amazon.com and consumers!
2. MUCH more secure. Credit cards are notoriously insecure. With one card-issuing bank keeping track of all transactions, theres a single point of failure for a hacker to attack and steal your information and money. With Ethereum and other cryptocurrencies, that transaction record is distributed between millions of computer systems. Even if one is hacked, the other records are still there (and end up overwriting the hacked version), making transactions MUCH more secure and virtually eliminating charge-backs.
3. Consumers control their money. Why trust a 3rd party to keep track of your transactions when you dont have to? While some fiat currencies are stable and you may trust your bank or government to control those, others are not. In many countries consumers must convert their local currency to another (incurring additional fees, losses due to exchange rates, etc). Ethereum is easy to access and hold onto, and works the same (and at the same value) everywhere. And the consumer stays in control of their money.
4. Privacy included. Current e-commerce fiat currency payment methods require the collection of consumer information to help fight fraudulent transactions. With Ethereum, transactions can not be faked or reversed, so theres no need for personal consumer information to complete the transaction.