This is not because anyone wants to discriminate against Americans (maybe they do, but it’s unrelated to this rule), but because of rules the US forces on the rest of the world. There are special tax reporting rules for US Persons that banks have to obey if they want to be able to do business with the US at all. If you can’t or don’t want to follow those special rules, avoiding having US Persons as customer is the easiest way to comply.

I’ve worked for several Dutch banks, and US Person is a special category they have to deal with. No other nationality has this. Maybe Ethiopia? But that’s easily ignored. But nobody ignores the US. They have no choice but to comply. Vote for a different tax code if you don’t like it.