No juries are not perfect justice. But then neither are judges. But of course, if you want a higher conviction rate, a highly prejudicial test for a case applied by lawyers, judged by lawyers of ordinary people, then this is it.
For my part, jury trial makes the best of the “beyond reasonable doubt” that requires conviction. It means that unless 12 people (or a majority) really are sure, then that person is acquitted. End. That is what I mean by liberal. It doesn’t allow the prejudice of one judge to have the decision as judge, jury and executioner (sentenced). We used to think that was a bad idea. It still is, imo. You can look at the Diplock courts (now thankfully gone) in NI for some of the drawbacks.