only 17/448 (~4%) million EU citizens work in other country than their birth one. expatriating is not as common as you'd think living in a major EU city.
However, ~1M goes back every year, so the affected people are more than the ones _currently_ living abroad.
Moreover, there are services that also intra-EU tourists can benefit from: - buying products >18 y.o. at automatic machines - simplifying buying drugs at pharmacies (we have EHIC, but it doesn't cover not-urgent care) - having fast track at airports without having an EU passport (in many countries people have an ID but not a passport) - easier lookup for police during random checks
[0]: https://ec.europa.eu/social/main.jsp?catId=738&langId=en&pub...