Had roofers redo the roof awhile ago. I checked the lawn for errent nails thinking I'd find none or two. It went from mildy to infuriating.
Having been a roofer before, that's a lot but not wildly large, especially if they were redoing an asphalt roof. We were always much better than this, but we did standing seam. Most of it is probably from removing the old shingles. If you're roof is like a 9/12 or steeper things just fly off that roof.
Again sloppy work, but I've seen so much worse from crews that don't care.