The main purpose of this paper (responding to encouragement of European Commission) is to present the authoress' opinion on the following matters: - the possibility of definitional differentiation of public sectors of general interest and these of general economic interest (SGEI); - that there is the purely economic rationality of financing by governments some public service obligation in the services of general economic interest; - that there is the future possibility that CE might find it a better solution to finance public service obligations although now the duty lays on Member States exclusively. The methods used is the comparative analysis of the EU documents (both regulatory and analytic) and theoretical and empirically verified approaches presented in appropriate economic theory literature and World Bank works. The paper points out that (contrary to the Commission's approach) the economic theory literature proposes the criteria enabling clear division between the two groups of services of general interest, and proposes the most appropriate definitional approach. On this basis it is shown that SGEI have the common characteristics which cause that some type of investment is being considered by private capital as unprofitable. But for governments having a longer perspective and including in the account externalities it turns out to be the very profitable 'public service obligation' investment, increasing competitiveness of national economy. The national differentiation of identifying public service obligations does not help creating paneuropean SGEI networks. This theoretical impact indicates the necessity of further studies on European legislation on services of general economic interest in the direction of consolidation of regulatory framework concerning SGEI and unification on European level of the public service obligation goals for them based on broadly understood efficiency criteria.