I, too, am confused by the question. I know of no "extra" braking systems available. The vehicle doing the pulling is generally considered "the tow vehicle," and no government in the world that I have ever heard of allows any self-powered vehicle on any public road unless it has a braking system. "Extra?" Never heard of such a thing, however.
Because the question makes no sense to me, however, I'm going to make a wild-eyed guess as to what the OP meant to ask: is it necessary for a vehicle combination such as a truck and trailer, or a motorhome and trailer/towed-car to have functioning brakes on the towed trailer/car. This would require both brakes in the towed part and a control system of some sort in the towing part.
The answer to THAT question is "maybe." And maybe relates entirely to the weight of the towed part. All governments that I know of require it, save for exceptions for light trailers/cars. That is, if the trailer is below a certain weight, then no brakes will be needed. What that weight is varies from location to location, but in the US and Canada, that generally is in the 3,000 to 3,500 lbs range, although there are a few as low as 1,000 lbs.
