Read up on FATCA (https://en.m.wikipedia.org/wiki/Foreign_Account_Tax_Complian...) before you argue further down that path. The US already has extraterritorial laws that have to be enforced by banks worldwide that don’t operate in the US.
Note that a common response by foreign banks to FATCA is to refuse to do business with Americans, which is very likely the best course of action. So it shouldn't be surprising when companies take similar precautions because of GDPR.