Toyota, Honda, Infiniti, Lexus, Nissan, Mini, Volvo, Audi, Mercedes Benz, BMW and many others all have drive-by-wire throttles. The reason many of them have it is due to how the fuel and air are being regulated today.
Mini and BMW use dynamic valve trains (lift and duration) to regulate the flow of air into the engine, in combination with varying the pulse width of the eletronic injector. How are you going to hook up a cable to that?