Because voters decided there was a common interest, cultural identity, etc. and mutually agreed on political integration. Voters clearly do not want a unified Americas.

The purpose of a Republic is to be a stable entity that ensures the welfare of its citizens. It is not to have a single-minded obsession with global welfare at the expense of its own sustainability or the desires of its citizens.

> voters decided there was a common interest, cultural identity, etc. and mutually agreed on political integration.

I'm less confident that this was performed in either ___location due to direct democracy, and more because it made political sense and was expedient at the time that these locale enacted the governance structure.

In other words, it's not a one-and-done-forever type discussion, and things (clearly) evolve over time.