the longstanding reason that other countries didn't institute their own more permissive drug laws were because the US would presumably penalize them but with Cuba it's definitely something else keeping them from changing it. I presume it's mostly because it's not a huge issue for the ruling class there especially compared with political dissent problems since nobody is going to give you international court bullshit over following international treaties you all signed... but at this point it probably is changing sooner than later.