As far as I know, Eurozone businesses and individuals can have their bank account anywhere in the Eurozone. Paypal and Stripe may only have offices in Luxembourg to serve all EUR countries. That's the upside of a unified market. The UK and other non-EUR countries have renounced to it.
You don't even have to be in the eurozone, I know UK companies which have euro accounts with international banks such as HSBC, which sit alongside their sterling accounts. The same goes for dollars, and probably other major currencies as well.
