This article investigates why school choice is exercised to a limited degree by parents despite major government initiatives to enhance diversity, competition and choice in the Danish education system. Denmark has had 20 years of centre‐right governments, promoting choice reforms perhaps even more vigorously than the other Nordic countries, yet school choice is seldom used – only 12% of parents choose a public school that differs from the one that is allocated to them. The literature on school choice in Denmark argues that this is primarily due to a general lack of parental interest because of the relatively high similarity across schools. In this article, we argue that the main reason is to be found in the politics of vested interests, namely municipalities’ persistent use of pupil assignment schemes supported by powerful teacher union branches at the local level.