"Most states require some manner of braking system for toads."
Please prove that statement by showing the State Statutes that require a braking system on a towed vehicle.
Please do not use any "List Of Towing Laws" found on the internet, and sponsored by the manufacturer of a towed vehicle braking system. I have yet to see one that is accurate.
Please do not use trailer braking laws. Many states do not class a towed vehicle as a trailer in their list of legal definitions.
However, most states DO have a mirror of the FMVSS Braking Performance Requirements codified in the state statutes. Here in Montana it is MCA 61-9-312.