The big differentiator is how attacks can be scaled. Most people/companies aren't individually a worthy enough target to develop an attack against a reasonably protected system. But with a lot of these types of attacks one can compromise a large number of systems in a largely automated manner, without risking ones personal physical security.
So it's possible and it's just a matter of optimization. Pens and typewriters leak data acoustically, so let's replace cameras with microphones to reduce costs. Tiny microphones with antennae can be mass produced cheaply and they are easily hidden. Delivery can be automated too, but it's much easier to embed the spy devices in common products people frequently buy.
