I have had 2 different instances of delivery drivers knowing about as much english as I know spanish, but they were eastern europeans. One showed up in shorts and a shirt, then changed into long pants and no shirt under a safety vest. He'd tried to avoid doubling back after dropping the load on top of mine, but we couldn't lift the 3 5,000lb loads on top of my load, so he had to drive off 300 mile round trip for a delivery then back to us. He at least knew what was going on.
The other time was a pair, same region, but they knew maybe 2 words. Exactly like the scientist from Stranger Things. It was hilarious, and pretty damned terrifying.
But the worst one was a mid 20's white dude that was straight up nodding when he got here. We asked him to unstrap the load, and he went to drop the whole damn trailer. When we were finished, he backed all the way down the road in front of our building, stuck his trailer through an intersection until he could turn the cab down one road of the intersection. We all just stood in awe that he didn't get smashed by one of the 50 cops that fly through there every hour.