OK then it’s our payment systems that don’t allow it. Probably by law?
When you cross the Great Belt toll bridge in Denmark, you can pay with the universal “Dankort” without authentication, but they have a special permission/agreement for that.
I don’t use Amazon, but on Steam we used to be able to make unauthorized payments, but that is not possible anymore last I tried.
I actually considered trying it to see for sure, but I can’t think of anything worthwhile to buy right now.