Vehicles that bank, and those that don't put different loads on the wheels.

On a two wheeled bicycle, due to the fact that the bike banks for turns, the wheels take minimal side loading, basically only when "throwing" the bike when off the saddle.

A two wheeled trailer puts side load on the wheels when it corners. Giving the wheels slight negative camber (leaning in at the top) not only gives the trailer a wider and more stable stance, but decreases the side load on the more heavily weighted outside wheel.

Burley dished the wheels a bit on the kid hauler I tow. This gives it a wider track, and helps keep the side panels out of the tires (still a problem) but it is exactly the wrong thing to do from a strength standpoint. (they are stronger if installed "backwards")

Wheel strength is only likely to be an issue if you use a highly dished rear bike wheel on a trailer. In this case, install it with the cog (flatter) side toward the center for best strength.