In the U.K., owners of televisions receiving broadcast signals (and now VoD) are required to pay for an annual license. The enforcement of this is mostly through sending letters, but there are also TV Detector Vans [0] which work in a similar way to TEMPEST — or at least, that's allegedly how they work because there's some debate about whether they really exist or if they're just a PR tactic.
[0]:https://en.wikipedia.org/wiki/TV_detector_van