Until now, people from mostly the poorer and developing countries were not part of the global community when it comes to places like e-bay or amazon, because almighty Paypal won't let them, but bitcoin have leveled the play ground and anyone with some coins can stop by to shop.
Until eBay or Amazon actually accept payment in Bitcoin, people are still limited.
Right now your only option would be to get a BTC credit card from a company like Bitpay or Xapo
https://cointelegraph.com/news/6-cards-battle-for-bitcoin-supremacy-bitcoin-debit-card-comparison-testand use that to shop on Amazon.
Which means you are still incurring additional fees and being forced to use a third-party service.
Thats IF you can even find a way to convert local fiat currency to Bitcoin.
We need easier ways to convert fiat and more ways to actually spend BTC if the market is going to grow and make online shopping more accessible to people who can't use a service like paypal.
I have a different understanding on what you are saying, to be able to use that card you need to fun your account with your bitcoin, so for me it's mor like a debit card than a credit card. Please correct me if I am wrong..