We build our heavy duty trailer with 2.5mm checker plate steel for strong walls and floor, stronger guards with side steps, thicker and longer drawbars and higher rated springs.
A box trailer is only as good as it’s engineered and built.
The key areas that fail are the brakes, wheel bearings, floor, drawbar or springs. In nearly all cases of failure, it is because the trailer is constantly being overloaded and/or the trailer was poorly maintained and is often unroadworthy.