old guy, in 14 years of towing, at about 10,000 miles per year, on some very rough freeways and forest roads, we have had one blowout in (wait for it) Oregon, in the McKenzie Bridge area near Eugene. And the tires were older than they should have been -- at that time, I did not know that trailer tires have a limited life span.
Now that I know to watch the tires like a hawk, to keep track of their ages, and to get beefier tires than I need (Load Range D on a 2500 pound trailer), I am less apprehensive about blowouts.
But I can't deny that a blowout on a single axle unit is much more serious than on a double axle.