According to teh UCI rules a road bike must have two brakes. Nevertheless I see on the very bikes only one.
I think it was in a time before the UCI had disapeared up its own backside and common sense prevailed as there's not much stopping power needed when you are going uphill.
I agree with you, but nevertheless I can recall a world championship cyclo cross somewher in the 70's where nobody less tham Roger de Vlaemink did race with only one brake. he got a penalty at that time. And race was not the right word. It was awfull weather and more running than riding. That's why he decided to do it eith only one brake.
Jan Janssen 1976 (caballero 1970 team replica)
Koga Miyata Gents Racer S1980 (in use by my son)
Giant Peloton Superlite 1998-2002
Diamant cyclocross late 80's
Favorit Czech 1978