There appears to be a big fundamental problem with this design in that the trailer is not articulated. While this will indeed make it easier to reverse, in some circumstances it is potentially very dangerous as whenever you turn a corner the rear of the trailer will swing out into the adjacent lane or footpath.
I'm pretty sure that this wouldn't actually even be considered a trailer under EU regulations and in any case they are required to be connected to the towing bracket using an approved ball hitch.