not agreeing with that at all. in the last 10 years I have had 1 ST failure (factory tire 6 years old) and 1 LT failure on my truck. both road debris issues in construction zones. but what I will concede is that the bottom of the barrel ST tires is what everyone is comparing their LT tires to, no one runs top tier ST tires and wishes they were running LT tires.
here is a good explanation of the differences and why you shouldn't run st on a car and why you shouldnt run lt on trailer
"Trailer Tire requirements differ greatly from automotive tires. Automotive tires must maintain traction during all driving conditions: pulling, stopping, turning, or swerving. Because of this they must have more flexible sidewalls to maintain tread to road contact. Since trailers have no driving torque applied to their axles, the only time trailer tires must have traction is during the application of trailer brakes.
Trailers with heavy loads, high vertical sideloads (like camper trailers), or trailers with inadequate tongue weight can be affected by trailer sway problems. Automotive bias or radial tires with their more flexible sidewalls can accentuate trailer sway problems, whereas the stiffer sidewalls of the ST (special trailer) bias ply tires help to control and reduce sway problems. For this reason it is not recommended that (P) Passenger or (LT) Light Truck tires be used on trailers. Best trailer control will be achieved with (ST) Special Trailer tires."
as for testing it is pretty much identical except for two tests, the P tires have one test that the ST does different, and the ST has a much more extreme full load test so how is that inferior, they are testing for two different things as neither is supposed to be used for the other.