I hesitate to put in my two penn'orth to this discussion because I am inhibited by the level of competence and expertise shown by all of you. Nevertheless, I am fairly confident that in Britain, right hand lever for front brake goes back to pre-WW1 days. There was a fashion for clean bars in the early years of the twentieth century and, because of that, the lever and rod setup is difficult to change. Survivors usually have two brakes with the front operated by the right hand. More sporting machines ,with a fixed wheel, had one brake on the front often operated by a short pull up lever, then known as a dwarf lever. That was fixed so that the lever pointed to the right. Early motorcycles with stirrup brakes followed the convention. The standardisation is rather odd in an era when car controls could not have been more varied.
Stuart Tallack in West Sussex