What do you mean it works in Ryanair and easyJet? They're operating completely different business models primarily characterised by rapid growth. SAS, like all other eu legacy carriers are seniority based as they have been around for ever and don't expand like crazy. Once the market is saturated (so like, yesterday) ryr and ezy will stop their explosive expansion which will lead to no more DEC. Furthermore, seniority systems will be demanded by the pilots in order to protect their careers.