Bronica had the good sense to make a switchable 120/220 back during the era of the S,S2,S2a,EC,EC-TL, and there are some cameras with non-interchangeable backs that have this facility. I suppose it never became a norm because of the added mechanical complexity and maintenance required/risk of failure. Those Bronica 12/24 backs can be finicky, but fortunately they're cheap.