While a braking system is a very good idea, it is not required by law in many if not most states.
Some states AND the Federal Motor Vehicle Safety Standards (FMVSS) have a braking performance law. ANY "combination of vehicles" (a motorhome towing a car is certainly a "combination") must be able to stop within a specified distance (usually 40 or 45 feet) from a specified speed (usually 20 mph) on a hard, dry, clean, level surface.
Most of the supposed "towing laws" that are referred to on the various lists on the internet actually are for TRAILERS, and the legal definition of TRAILER in many states specifically excludes towed motor vehicles!
AFAIK, none of the various braking systems available have been tested by any independent testing organization, such as Consumer Reports or Good Housekeeping.
I agree, the Ready Brute Elite integrated towbar/surge brake system or the Ready Brake braking system that can be used with any towbar is, IMO, the best of the bunch!