People don't make a company. Stripe exists as is because it's not a EU company.
Quite to the contrary: all a company is (at least as originally conceptualised) is the formalisation of a group of people, usually working together towards a shared goal. It’s in the name - just like you have a troupe of actors, you may have a company of engineers and accountants (though to keep in the vein of live stage production, you also have a theatre company).
This is why we tend to use collective pronouns when referring to a company - Meta just announced that they are planing share dilution (though to weaken my own case, one can also use singular nouns, likely due to the increased modern perception of a company as a single entity due to the increased anonymity afforded by the internet)
Why though? Because they raised a lot of capital in the US? Or because they had access to better talent in the US?
As I see, there are many payment providers in the EU, just not API first as Stripe ever was.