It's near certainty that we as RVers won't be stopped/screened/random checked for towed vehicle brakes. Nor weighed nor asked to do a stopping distance test. The only place I've heard of that was serious about towed vehicle braking was British Columbia.
What's highly likely is an investigation coming out of:
An Accident
A Toad Disconnect
Some Traffic Violation
Just as an example, our RV says "Coach Brakes are intended to work at GVWR (Weight of Loaded Coach) **NOT** GCWR (Coach plus Toad/Trailer)." A LEO or accident investigator will pick up on that and establish that we did not act as a "Reasonable Man."
So let's not be Truck Stop, Jail House, Camp Fire or Key Board Lawyers. Let's just do what makes sense to stay out of Harm's Way.
Too Much Brakes? That's like "Too Much Money, Girl Too Pretty, Car Too Fast."
Towed my Pickup taking the RV to the shop. Short trip, didn't put the Brake Buddy in. On the way, Sorry I Didn't. One of those White Knuckle Stops.
Started towing the Corolla in place of the Pickup to have about 1000 pounds less back there. Glad I did.
Weighed the coach and found it right at GVWR. Upgraded its brakes. That's right, new, higher capacity components. Hurricane evacuation in loaded RV towing loaded Pickup with Brake Buddy on crowded Interstate, Glad I Did.