It would be if we could always assume that people committed them. Unfortunately, as I pointed out in the post you quoted, the US justice system has a rather high false-positive conviction rate. When you add to that recent video evidence of cops planting false evidence on people before they were even arrested, there's no way to be sure about any "conviction." Even people who "confess" are often told to take a plea deal to avoid being tossed down a dark hole for decades of their life. My own personal experiences as a juror on "felony" trials were very eye-opening as to how little interest there is in "the system" for getting "justice." It's easy to sit in comfortable suburbia and condemn "those criminal types," and cheer on the various federal agencies for making sure they "pay their dues." Real life isn't anywhere near that simple.