You can find your barcode both on the web and through Amazon's mobile apps, and there are shortcuts (such as a home screen icon or Apple's Wallet app) if you use it often.

The cash option is only available in the US and is limited to a handful of retailers (CVS and Speedway are among the examples). It's safe to say that Amazon's most direct competitors (Best Buy, for example) aren't about to cooperate. Still, it's a big deal for both Amazon and shoppers. As TechCrunch points out, more than a quarter of American consumers rely primarily or exclusively on cash. This lets Amazon reach a wider audience, and gives these cardless customers a chance to buy products that are either hard to get offline or more affordable than they are at retail. In other words, they won't be cut off from one of the internet's bigger advantages.