Because it's called driving around for 40 years and basically seeing the trend die out? Waze does it for you. Who is going to spend money on this when the answer it's something that's gone out of style specifically re the cop thing? Flashing for passing and intersections (as well as tailgating assholes) is still a thing but the idea that it's one if by land 2 if by sea is not widely used. It's just flashing. Or not. And rarely for cops because the apps have taken over.