While this *might* be relatively innocent tinfoil-hattery, it could also be an amazingly cost-effective example of asymmetric warfare (target the most gullible minds with a conspiracy theory that gives them an incentive to vandalize transport infrastructure):
Pensioners attack Devon traffic lights over wild 'deadly weapon' claims
An online movement say that the sensors on traffic lights can cause heart attacks, brain cancer, anxiety and even sudden death
https://www.devonlive.com/news/devon-news/pensioners-attack-devon-traffic-lights-11148748
@cstross “the medical and technological claims made by the group have not been independently established” is a rather weak phrasing for saying “utter poppycock”