It's more simple. Small air forces like to use the same jets as their allies because it reduces costs for everyone. It means there's a larger pool of people qu

It's more simple. Small air forces like to use the same jets as their allies because it reduces costs for everyone. It means there's a larger pool of people qualified to fly and work on the jet, nations can do maintenance deals with each other to reduce costs, parts supply becomes less of an issue, air forces can fly to allied air bases and know that the tools, infrastructure, and mechanics are available for their jets, training costs and resources can be shared between nations, flying and integrating with other air forces becomes easier, shared experience on the same jet helps identify and resolve issues, etc., etc.