Yea its kinda crazy, i live in CA and i have never seen a residential yard ever mowed with a 36" or bigger mower.....ever!!!
You would be surprised at the massive lawns that are mowed with 21" mowers. Some of these are huge mansions and they will have 3 guys mowing for hours at a time. IMO, a huge lawn mowed with a 21" looks ugly.
But the majority of lawns are small so i understand why most wouldnt have a trailer.