There are mechanisms to enable the towed vehicle/trailer's brakes to be activated when being towed on an A-frame - although I admit I've never used them, and have some doubts about their effectiveness. Generally speaking in this country the "turn a blind eye" approach has been taken, although many years ago when driving a 7.5 tonne MAN recovery truck with a car on the bed and another on the A-frame a motorway cop did stop me (on the pretext that something was dangling below my "trailer") and then point out that the trailer was unbraked. I didn't argue of course, but merely suggested that as the truck was braked for a train weight of 8.25 tonne and the total all-up weight was probably less than about 6 tonne I had adequate capacity.....he wandered off saying he was only commenting.....
