Since many, many decades these drive sizes 1/4, 3/8, 1/2, 3/4 are standards fixed in ISO or German DIN
(I guess it is today ISO 1174 and DIN 3129 - you cannot get these documents for free).
If you go back in history, there were also other drive types as e.g. hex drives
as this HAZET 240-59 from...