This chapter deals with the compensation of SGEIs in the transport sector. It discusses the recent Lux Express Estonia case, and its broader implications concerning the difference between the public procurement procedure and regulation through national legislation. It argues that the public procurement procedure brings forth fewer risks with respect to potential compensation of the provided public service. This is especially relevant in light of sustainability requirements, because compensating for ‘sustainable SGEIs’ may result in compensating unsustainable companies and thus breaching the polluter pays principle, as this chapter demonstrates.