When I upgraded my Mac to El Capitan, I noticed that my old U.S. Extended keyboard (complete with U.S. flag icon) has been replaced with the ABC Extended keyboard complete with a new A icon. There’s actually a series of ABC keyboards including plain ABC (a Latin script default?) and ABC Azerty (under French keyboards). This is mentioned in a few places online, but all I can say is Quel surprise!.
FYI – Some people will be relieved that the PC U.S. International is still available under the English keyboard listing.