The point of the film is to show how horrible war is in a context Americans can relate to. If they made a more realistic alliance, down some sort of real life right / left politics the message would be lost and it would be held up as some sort of propaganda film by one side of politics with the other side using it to justify why they’re correct.

So, yes the “alliance between the California and Texas” is a very deliberate choice.

You either die hero or live long enough to become sleepy Joe.