For county, several times I called & didn’t need to attend.

Federal, I did have to serve as a juror this year. They always start on a Monday, I think everyone who they pick has to attend for selection, then most are sent home. The way they pick is public information. I am lucky, the courthouse was close to me and accessible by bus or bike. But they pull from 3 counties, some jurors had to come from far away. Case took one week. I didn’t want to do it and my workplace needed me but I am glad now, it was an interesting experience overall.

And yeah it’s mandatory to show up if you are told to. You can be fined or even jailed. If you can’t, you need to ask for a deferral or excuse. I got a deferral of one week because I had a dentist appointment I’d already postponed once, which had delayed it two months so I really didnt want to wait 2 more! And other times when I was nursing kids I sent an excuse, and once a deferral for work, but Federal court won’t excuse you for work - our judge did dismiss anyone who really would not be able to survive without working though.