GDPR only applies to American companies if they either have a presence in Europe (through an establishment or through a vendor processing personal data) or sufficiently deal with a clientele in Europe.
If the US tried to override the second part unilaterally, Europe would probably ban exempted companies from dealing with European customers unless they opted into GDPR or would otherwise fall out of scope without the exemption. They'd therefore have trouble dealing with European banks, shipping companies with a presence in Europe, etc.
Not to mention, what if Europe tried to exempt their companies from dealing with the annoying US laws? It would become a messy war of exemptions and consequences.
This game of "we're too special to have to follow your laws even if we want your customers en masse" is a dangerous game to play.
If the US tried to override the second part unilaterally, Europe would probably ban exempted companies from dealing with European customers unless they opted into GDPR or would otherwise fall out of scope without the exemption. They'd therefore have trouble dealing with European banks, shipping companies with a presence in Europe, etc.
Not to mention, what if Europe tried to exempt their companies from dealing with the annoying US laws? It would become a messy war of exemptions and consequences.
This game of "we're too special to have to follow your laws even if we want your customers en masse" is a dangerous game to play.