Not being a resident means you are the resident of a different country, so the assumption is that you have a bank account there. And being illegal or a suspected terror financer would already put you in an underclass anyway.
Governments are quite imperfect, and humans are a varied bunch. There are exceptions to everything , and exceptions to that. The Windrush generation is just a recent example that comes to mind: luckily, they were numerous enough to get their story heard. But people fall through such cracks every single day. Sometimes an imperfection in the law, sometimes an “overzealous” public servant.