Early analysis of this phenomenon was undertaken by English economist Arthur Cecil Pigou (1877-1959).
Price discrimination describes the sale of identical goods or services in different markets at different prices.
Pricing is usually linked to ability-to-pay; thus, students or pensioners may pay less than others for social services. On a larger scale, modern pharmaceuticals companies frequently sell the same compounds at radically different prices in different (especially European) countries because the local market demand will allow it.
A C Pigou, Economics of Welfare (London, 1920)