If I commit act X, which is illegal, but I cannot be convicted because an error in police precedure makes some of the evidence inadmissible, it sounds like you believe that means I did not actually do X.
That is not how causality works in this universe.
I don't think you know why we have trials. We don't have trials to convince everyone else. We have trials because your eyesight alone is not sufficient evidence, you need to consider all of the facts, not just what you think you saw.