I agree that it is not illegal to fake being a U.S. resident to keep firms happy, but the fact remains many firms are actively smoking out expats and they don't want their business. So expats are often forced to live in ethical grey areas about honesty.
There are cases where legal issues come into play. For example when renewing a state driver's license you may be compelled to swear and sign that you are really a state resident. If you aren't that must surely be a criminal matter if that was ever actually pursued.