It's also possible to bribe jurors to get off a conviction. Possibly easier than bribing a judge.
All classes of people are corruptible.
After all, if you don’t know who they are, you can’t bribe them or blackmail them. Same argument applies to the judge.
One-way-glass might be a work of fiction, but video cameras are not.
It's a bit silly to worry about that level of conspiracy.
But even if it weren't silly, there are easy answers. An oversight board, or revealing the jurors after the case is decided, or revealing the entire juror pool of 50 some-odd people, etc.
If I'm going to do something and want to bribe a judge I have years to research all the judges who might be at my trial (there are not very many). Each will have a different bribe that will work. (one doesn't want his wife to know about an affair; the next is in an open marriage and doesn't care but he has big gamboling debts that you can "take care of"...)