Radars jammers aren't legal (because radio waves are regulated by the FCC), but laser jammers are actually legal in most of the US (because light is regulated by the FDA):
https://youtu.be/vQtLms02PFM : popped out today on my YouTube feed, pretty relevant to this whole discussion (and also really worth talk)
Otherwise I'd think you'd see a lot of radar dector jammers on the market.