I think the weird American anomaly is that they’re so often still involved in policing, not that they handle legal paperwork. Other common law jurisdictions have sheriffs who deal with court minutiae, but policing was long ago hived off to a more modern entity.
Of course in at least some states the counties also have a “Marshal’s Office”. Who are uniformed police much like the Sheriff’s office. In places with both Marshals and Sheriffs, generally the Marshals handle the jails, the court bailiff duties, and the process serving. Leaving the Sheriffs to be ordinary law enforcement out in the field.
And yes, some states have state-level Marshal’s offices, and even the federal government has a (large) Marshal’s office.
People occasionally accuse our town planning board of taking bribes (not accusing formally in court, but in miscellaneous gossip.) The most we’ve ever even been offered was a batch of cookies.
I will admit that we ate the cookies; but will point out in our defense that they were delivered after we’d voted on the application, not before; and that they hadn’t even been mentioned before.
It had not occured to me that somebody might take to bribing the neighbors!
– the first part of that, approaching the neighbors before the public hearing in order to explain to them what you’re up to, we strongly encourage. In most cases the neighbors wouldn’t have to, or be able to, sign on to anything (there are some exceptions, though none of them involve the applicant suing the neighbors about it); but it does often make for quieter public hearings.
thx for all the answers (on sheriff serving paperwork in USA) … ignorance fought!
I assume there are historic reasons for that (e.g. lack of “burocracy / civil servants” in the nascient US in the 1800s)
It doesn’t have to be a sheriff. Anyone can serve papers. I served papers on two occasions to business owners who friends were suing in small claims court.
I had a very friendly divorce. Since I started the paperwork, my then spouse had to be served by someone other than me. In a contentious divorce, it’s obvious why you’d get a sheriff or a professional process server to do the deed. In my case a mutual friend signed the paperwork and “served” my ex.
In many states, Missouri is one, the sheriff is the chief LEO at the county level. He’s directly elected by the residents of the county. In the city of St. Louis, and perhps in St. Louis county as well, the sheriff only runs the courts and jail as mentioned above. But in most of the counties the sheriff is the chief LEO.
I might be wrong, but I seem to remember reading that even the folks who hate police will accept the sheriff’s authority because he is directly chosen by the people.
If there is anything that is consistent in the United States, it is the incredible inconsistency of local law enforcement agencies and what they police. The variability is absolutely massive - there is no single rule for anywhere.
Decades ago I was working at a job in a quite urban area, where some drunk had plowed his car into the front gate of our facility, gutting the car’s oil pan on the center island in the process. Quite a mess. So normally in a town in California you call the local city police department to report it. But though we were immediately adjacent to a dense residential neighborhood, our facility was just over the city border into a largely industrial unincorporated part of the county. Okay, well in that case you revert to reporting it to the county sheriff’s department which polices unincorporated areas (as well as contract to police some towns too small or broke to have a separate police department) - which we did. “Oh, no” they said - “it involves a vehicular incident so you have to report that to the California Highway Patrol.” Which is a statewide law enforcement agencies that usually writes speeding tickets on highways. Even folks that live here don’t always know the exact ins and outs 
.
You think serving papers in a civil lawsuit is an unusual activity for a law enforcement agency, how about the fact that US Marshals used to conduct the census. Up until 1870, in fact.
I think it’s extremely unlikely that a lawyer would send out 250 hefty sets of papers saying “you are being sued” to 250 people, if that was a false statement. It would be a very dumb thing to lose your license for.
Obviously I haven’t see the paper work. But one possibility is that the 250 people got a copy of the summons and complaint that were directed at the actual defendant and the summons said “you are being sued.” It was, however, just a copy that gave the OP notice.
On the other hand, it is also possible that the local law requires the plaintiff to bring in as parties every affected landowner. If so, they are, in fact, being sued.