Likewise in regards to the police: we had DuPage sheriffs wander in occasionally to look around and chat - they were reasonably friendly with some random chitchat. I don't think they were looking for anything in particular, just trying to deter any mischief by being seen openly.
One thing that surprised me is how hard election judges worked: I started by 6:30 AM and only ended at 8:30 PM, with maybe a 15 min break for lunch. All the other time I was handing out ballots, doing paperwork, giving directions, etc. In DuPage election judges get $100 for the whole day - I would be in favor of doubling that plus some money for lunch + dinner.
I also came away from it thinking "Oh goodness it is amazing democracy survives, but kinda cool that it survives in an extremely participatory matter."
Edited: Would have been for the primary, not the general, so I was still in high school, and the youngest judge by 50 years or so for our polling place.
That's it, you just don't get paid? I'd expect it to involve a criminal investigation.
* As a security/integrity issue, the ballots themselves are much less scary than the pollbooks, which are what we use to match voters against the voting rolls.
* Everything's ultimately on paper; there are bar codes, which nobody loves, but they're auditable against the readable printed ballot.
* Most of the security is physical/human; for us, each polling station (a location can have several precincts and thus several stations, each a giant rolling metal box) is sealed using numbered plastic seals before the polls open and after they're closed, and everything is recorded redundantly and signed off on by the poll workers.
* A matching count at the close of polls is a big deal, a nightmare big deal; in Illinois, we can't just shrug off a missing ballot and say "nothing we can do about it"; in March, I had to stay 3 hours late while we resolved a similar issue (IIRC, a mis-recorded provisional). Most pollworkers in my experience are there for the money (I've never bothered cashing the check) and the threat that they won't get paid if they count doesn't match is extremely powerful.
* The local police are not allowed to monitor polling places, and the municipality of the polling place is usually confused about that; in Cook County, it's the County Sheriff's Department that has authority over polling places. Our cops were very friendly and responsive.
* The drama of every election is the the "string line" that defined the 100 foot "no electioneering" radius of the polling place; the entertainment you can count on each cycle is the candidate whose people religiously move their lawn signs inside the string line, and freak out when you remove them.
It's an interesting system that derives a lot of resiliency from extreme complexity and maximal human touch points --- Illinois elections will never do something with 1 person when the same thing could be done with 2 --- which is sort of the opposite of how we reason about security online. It's simultaneously terrifying and reassuring.