Firstly, there would be enormous inertia against any change to the standard light arrangement that has developed over the past 100 years or so and come to be the accepted norm. read more
I’d guess the main reason is that front brake lights don’t give you usable information. Rear brake lights tell you that the car in front is slowing, it’s information that is useful as a following vehicle because you must take action regardless of whether that car in front simply slows a little or comes to a complete stop. read more