I’m an Aussie, don’t understand your SS system, thank you for your comments.
It is an old, political non system ‘system’. It goes back to the Civil War. To an extent, it is a draft of men by county. It is very locally administered, from the days of when it was thought that the local authorities would know who were the ‘free’ men that could be drafted.
There is a notion that better educated men were to be given ‘deferments’, while working stiffs with out too many children could be rounded up.
Really, just gussied uped, not much different than press gangs, with the exceptions of the elite that wanted to could game the ‘system’.