I doubt low tire pressure is much of problem. Most people I know inflate to max pressure to let's say 100PSI which is a common max pressure.
Tire heats up and it's not 115-120psi, now you end up driving in the south and it's Africa hot and the tires are now 130psi or more. Now throw in tires that have not been cared for their entire life. Not a good combo.
How many people put a water based UV inhibitor on their tires?
I suspect you'll find that age, combined with max tire inflation and overweight to be a big cause. LOTS of overweight coaches rolling around. I notice that most people who post in various forums about a blow out also show the tire is over 5 years old.
Tires can last longer then 5 years with actual use and actual use is better for the tires, but these things sit so often and long.