We unpack the FTC’s claims that Amazon used design to trick customers into buying—and keeping—a Prime subscription. If you’ve ever tried to end your Amazon Prime subscription, you may have found yourself embroiled in a disorienting multistep process that felt more like a choose-your-own-adventure than a simple cancellation.

Hands-down, one of the most impressive features we saw during a demo of Amazon’s soon-to-launch Fire Phone was Firefly, Amazon’s answer to real-time discovery. At first, it just sounded like a glorified barcode scanner: A button on the Fire Phone ...