This is really just a form of passive radar. It's using ambient signals instead of an active beam, but the analysis techniques used are essentially equivalent. It's like stealth technology in reverse. You are intentionally creating a recognizable radar signature.
Replacing shopping list was but one of the use cases given. I agree it's a ridiculous one, but there's plenty of actually useful applications for things interacting with RF that can be mass-produced cheaply.
Internal combustion engines are more important than just cars. They enabled powered flight. They enabled heavy construction and mining machinery. They enabled plenty of other high-impact things in our lives. And at the very least, they don't stink as much - towns eventually drowning in horse manure was a real fear in the times just before the first automobile.
That said, we're now on the verge of switching most of ICE uses into electricity, which can be made more renewable than horses. We'll be good, if we can make the transition.
