While I don't want to TOTALLY dismiss the thought of rotation, trailer tires live an incredibly similar life, while on a car/truck tires live very different lives.
Rear tires do the acceleration, and front tires do the steering...
Front and rear may carry very different weights, and at braking time, there's more opportunity for different wear and tear.
Conversely, the on the trailer the weights are the same, no one's accelerating, no one's steering and the braking is more similar.
Now I know why I've never rotated my trailer tires...