The taxation part of this is a bit of an unfair point. The US allows for an exclusion of ~$150k in foreign earned income if the US citizen qualifies as a bonafide resident of a foreign nation. On top of that, the IRS lets you deduct any taxes paid to a foreign government dollar for dollar against owed US taxes, and since most other developed nations have a higher tax rate, this essentially wipes out your US tax obligations (federal only, some states will still apply taxes separately). The only people actually double paying taxes are the ultra rich, but they obviously don’t pay taxes at all since that’s for the poors
Obviously, the system is still stupid and overly complicated (why should I even file a return with the IRS when I don’t owe anything?), but it’s not as egregious as this video makes it out to be
It depends, since all states manage their taxes differently. Usually it’s done via determining ties from the foreign resident to the state in question (e.g. is the resident receiving mail, operating a business, or residing x days of the year in the state?), and taxing on that accordingly. My state doesn’t collect income taxes, so I’m not well suited to speak on this topic.