One thing you're missing:
For the average person, jury duty can be a scary, nervous, anxiety-ridden experience.
Last year I was called for jury duty for the first time in my life. I'd only been in a courtroom twice before that: once accompanying my daughter to traffic court (the person who hit her and was ticketed was protesting their ticket, so we had to be there); and once for a custody case.
They'd pulled a large pool of potential jurors for multiple cases for that week. Officers of the Court (assistants) put us through a training video and a verbal lecture on what we were and weren't allowed to do or say, including things like whether or not we could leave the building or the grounds. While the officers were friendly at times, they also did a good job of transmitting their own anxiety over the judges to the potential jurors.
I spoke with several other people at different times on different lunch breaks, and they all said pretty much the same thing:
Jury duty made them nervous. Most were worried that if they did the wrong thing, spoke about the wrong thing, they'd not only screw up some case... but also, might be held in contempt in some way, possibly facing a fine or even jail. Some were nervous about the kind of personal information that might have to come out during the selection process, and they were right: people ended up having to talk about various family members who'd been arrested, or themselves, for various things. People ended up having to talk about having been sexually assaulted, or family/friends who'd been, or who'd been victims of other crimes. I understand the judge and lawyers need to know those things for some cases, but it's still harrowing.
While with some questions we were able to defer answering until we were brought in solo (not in the group) to help protect our privacy, at the same time, there were people constantly coming and going in the back of the courtroom (audience), and we were told NOTHING of who those people were. So not only were you discussing this stuff in front of the judge, their security officer, stenographer, clerks, the prosecution and defense lawyers and the defendant... but also random people in the back of the audience area. We also had to confirm our name, address, occupation, place of work, and a good bit of other personal information in front of those random people.
Now, imagine that you're in a jury pool for a violent crime, say a rape trial. You have to tell all that personal and often uncomfortable people not just to a room full of court workers, not just in front of the accused... but also, people who very likely *may* be family members of either the accused or the victim. All those people now know where you live, how many kids you have, where you work... and if you get picked for the jury and the verdict makes someone unhappy, THEY KNOW HOW TO GET TO YOU.
Plus, again, what if you say one word at the wrong time and place, and cause a mis-trial? What if there's a miscarriage of justice because you slipped up or were stupid?
And looming over all of it is the judicial system made real, that same system where you've heard countless stories of injustice, of capricious judges, of judges actually violating laws with their rulings or even experienced it yourself. One place in particular where people run into that a lot is family court: judges sometimes rule on visitation rights or even custody where they violate law---for instance, mandating visitation for a child old enough to choose *by law* who they will and won't visit or live with, and often despite various types of abuse. Yes, many people get traffic tickets and some end up in court---but I'm willing to bet that there's very few people who haven't either been through family court for a custody case and/or a divorce, or had friends and relatives who have---and family court is an especially tense prospect for people, because the disposition of someone they love is riding on it.
In short, between personal experiences, stories of family and friends, and stories in the media about capricious judges, hung juries, mis-trials, and contempt of court rulings... most people walk into the courthouse doors full of anxiety, when called to jury duty. That's on *top* of the anxiety caused by having to take off work or arrange child-sitters, the unpredictability of the schedule and the hours, and in general, the disruption to your daily life. Everyone dreads the thought of being on a jury in a trial that takes weeks, involves staying in a hotel, etc. Then you pile even more anxiety on by how they conduct themselves, the rules you must follow, and strangers hearing personal information from you.
Given all that, even the most civic-minded potential juror (someone who is determined to do their duty to the system) is likely to be in an intimidated state. Most don't understand all the laws, rules, and regulations... so again, when the court (judge or clerks) instructs them in something, they tend not to challenge it, or even know that they *can* challenge it. In my case, we weren't really told anything about what we could challenge or refuse to say---and there's the fear that if you refuse to answer, they'll think "what is she hiding?" and sic someone on you to investigate you... even if it's just that you're too uncomfortable to talk about something. There's the fear that refusal to serve, or refusal to answer, may get your taxes audited, or get you contempt charges, jail, and fines.
People in that state are far more pliable than they are in normal life. Authority looms over you.
It's not surprising that juries who don't understand the law themselves, and who are often in such a state of personal anxiety, take incorrect instructions from activist judges without a murmur.