I am but a meager low time private pilot, but I'm sure this happens all the time as it has happened to me. Before I got my certificate, I departed my home (towered) airport solo planning to buzz over to a nearby very small uncontrolled airport and practice some landings. When I arrived, the city mower was working around the runway, apparently not listening to CTAF. I aborted the first landing as he crossed the runway just in front of me.
Fortunately, he was just finishing the area around the runway and I was able to continue practicing without any further issue.
From a safety standpoint, it was never a big deal. I saw the mower, was aware of his location, and watched to see if he would depart the area before I got close to the ground. He didn't, so I performed a go around. I was surprised that he seemed not to notice me, but it was more inconvenient than unsafe.