Perhaps the whole issue goes away with the advent of EVs, which I believe can not be flat towed.The rules written with trailers in mind. The most common failing there is the coupling separating from the towball. Either a breakaway cable or a secondary coupling would achieve the objective there.
Only once in 30 years have I known a drawbar fall off a trailer. But that is the most likely failing where an a-frame is concerned. In that scenario, both breakaway cable cable and secondary are ineffective, they are still correctly attached between ball and coupling!
This is precisely why Trailer braking regulations are not fit for A-frames.