Because false positives are a thing and cops who stop, attack, kill, arrest, detain, lay hands on, attempt to interrogate, approach, or otherwise darken the days of the innocent are not, themselves, terminated, charged with assault and kidnapping, and locked away never again to breathe free air or to look upon the sun or sky without bars interposed. Nor are DAs who charge (lie) the innocent or judges who go along and allow these shenanigans.
See to it that the police, DAs, and judges are all properly punished when they play their "close enough for government work" game; them we'll talk about giving them more power. Until such time as they are held accountable when they abuse the public, fuck 'em.