A third, high center mounted brake light (that only lights when you depress the brake pedal, or gets significantly brighter) has been mandatory on US passenger vehicles for ages now.
I don’t understand people saying they aren’t designed to be functional, no matter which model year or trim you have.
“The National Highway Traffic Safety Administration (NHTSA) repeated Voevodsky's experiment on a larger scale, and concluded that center high mounted stop lamps, as the government calls them, reduce accidents and injuries. As a result, in 1986, NHTSA began requiring all new cars to have a third brake light.”