Every country has different requirements based on their environment.But why do other countries get the same plane but some of the features are left out, and what if those were things the other countries wanted?
Some Nordic Countries need Parachute Brakes on landing, not every country needs that because they don't deal with ice very often or at all.
Some Countries need testing to deal with Jump Ski Ramps on their carriers for the B-variant, some don't care at all and go for the A variant because it's the cheapest.
Every country works with LHM and the DoD to get what they want.
Not everybody needs the exact same feature, but the basic AirFrame can support each feature.
If you're worried about weapons compatibility, UAI (Universal Armament Interface) is the new US Open 'Plug N Play' standard for all existing and future armaments.
No more hard coded firmware in the OS to deal with weapons.
Basic Driver packages will be all that's needed.
UAI is getting retrofitted into all previous and existing platforms as we speak along with legacy weapons getting updated to support UAI.