I thought apps like trapster were taken offline because police objected.
Also relying on other people is not as reliable as using the police’s own vehicle lojacks.
IIRC, the cops were trying to negate Trapster's effectiveness by making false speed trap reports. Trapster countered by adding a "confirmation" feature, allowing users to either confirm an active speed trap or report it as false or inactive. Works well enough to tick the cops off.