Why do funding bodies like the Swedish Research Council mandate Open Access – if Open Access has advantages, e.g. more citations, wouldn´t more authors use it anyway?

Experience has shown that mandating Open Access accelerates the pace of change. Hence many research funding bodies have decided to require Open Access. The example of the National Institutes of Health (NIH) is illustrative. When they simply recommended Open Access, the response was negligible. The situation changed drastically when they decided to mandate Open Access.