" You and I were speaking toward different scenarios."
Because YOU HAVE NO CLUE. You didn't even understand THE CONCEPT. Nobody even SUGGESTED taxing Iowans.
But if an Iowan makes money in NYC, they're taxed by NYC and NYS.
Then, their home state MUST CREDIT THEM the amount of taxes they would have charged on that same money, capping at what you paid to NY, or your home-state liability, whichever is less.
" Sweden, Germany, Norway, the UK, Denmark, Canada, Finland, Australia, and New Zealand"
Correct me if I'm wrong, but isn't this a list of the happiest countries on earth?