Three things different between ST tires on a trailer and LT tires on a pickup.
1. St tires are often subjected to curb hopping without any knowledge to the driver. I see it happen often in crowded service station scenarios.
2. ST tires are flat spotted from improperly adjusted brake controllers. I have seen smoke come off of ST tires when someone has had to make a rapid stop at a stop light. I have also seen it on long drown grades probably because the brake controller was a time based unit with gain set too high. This can lead to a tread separation failure at a later time.
3. ST tires are run at speeds greater than 65. I see this every time I am on the freeway. When you are going 75 mph and have 5th wheel trailers pass I can only assume many have ST tires.
I have had more than my share of LT tire failures on my pick up over the last 40 years. Several tread separations and a couple outright blowouts.
I also suspect there are LT tire failures in trailer service just do not hear about them as often as the ST tire probably out numbers the LT by a large margin in trailer use.