There is another point, at least for Americans. While I know a few people who have emigrated to the US and still maintain ties with their original homeland, I know others who have intentionally given up their privileges back home. While they may still be citizens of their home country, they owe them no obligations.

The US is different, they tax your income no matter where in the world you make it. if you are living in a country with a tax treaty in the US, you can fully deduct all foreign tax payments so you will likely end up owing nothing to the US. But you still have to file. And in return for that you retain the right to vote from the state you last resided in. Furthermore, it is quite hard to give up your US citizenship. It can be very costly, because we will make you pay taxes on assets as if you sold them before they let you leave, including any retirement funds.

Americans living abroad are much more likely to still consider themselves Americans first, because we remind them about it every April 15th.