Why different rulesets?

[bsnalex]

This has been bugging me for a while - and it's not limited to softball, it's effectively every sport there is (except soccer).

But why in America do leagues and systems not play by rulesets that have been codified by the international governing body for the sport? I mean, the NBA doesn't play by FIBA rules, the NHL has it's own code. Softball has to be the worst perpetrators, having different rule sets for High School, NCAA, adult amateur etc. We've got NFHS, ASA, NCAA.

Why doesn't every system out there just play by ISF? At their hearts, the rules of the game are the same, but then each ruleset has variations on the semantics of the game.

It just frustrates me from time to time--selfishly because my fed plays ISF so alot of these rulesets are lost on me and the board doesn't give me the help i usually need