Eli5: Why do shoes have half sizes, rather than double the amount of whole sizes?

Question

Especially cause shoe sizes aren’t really universal anyway, making the half sizes even less meaningful. Why?

In: 193

Answer 1

The original shoe sizes used in English speaking countries were in barleycorns which is an old fashioned imperial unit for a third of an inch.

Also while they changed around what shoe and clothes sizes means a number of times, they learned that for female customers smaller number for size are more popular so switching some other smaller unit (like line which is 1/4 of a barelycorn and 1/12 of an inch) would have made the size number sound bigger and less attractive to some customers.