No criticism implied.
...
As you point out, you would run into fewer ugly situations if the societies were running from remotely similar premises.
It would be one thing to have Aus/Can/NZ outvote the President, or the U.S. Congress, 3-1 on matters of foreign policy. It would be a far different matter for Saudi Arabia, Qatar, and Libya outvote our SuperState on the question of whether women could drive. (Or whether the New Testament should be banned, or take your pick.)
The E.U. had recently revealed plans to ban plug-in English tea kettles. Moe Dawg used the word 'picayune' to describe the mentalities of these technocrats. The 20th century was full of dictators who were only too glad to control citizens' lives to the maximum extent possible, and often for the sheer joy in it.
But! I'm gathering a sense that SSI denizens would, 90%+, oppose this type of social control by a SuperState over the U.S.
.....
In WWII, we got all the players on the field and fast, but it didn't require anybody to relinquish their sovereignties or their cultures to do it, right?