Healthcare in the UK moves at a snail's pace. NICE requires a lot of evidence before they will permit new treatments. The bigger issue though are the "Daily Mail politics" of using drugs that can be abused - it's seen as politically toxic with a particular segment of voters. Take cannabis as an example - it was moved back to class B years ago, purely for political reasons. And as other nations are starting to use it therapeutically, we still seem light years away.