The main issue tackled here is that multinational corporations operate across borders, and thus create problems of capital flight out of a country. Thus, even if the economic activity is almost entirely happening within a country (e.g. a local shop uses locally targeted online ads, sold by a sales team working out of a local call center, to attract neighborhood customers), the profits could be captured somewhere else, like an Irish subsidiary handling profits from continental Europe. Even if those profits get reinvested or distributed to shareholders, they might not get reinvested or distributed in that country where the revenue was generated.