[tichiian]

Because Russia and Iran have leadership that has other sources of income outside of the sanctioning west. Cuba and Iraq had that historically (with the eastern bloc as trading partners), and the regimes began to change (at least a little) when those sources for income vanished. That they didn't immediately disappear comes from the fact that the respective leadership is caught between a rock and a hard place: uncomfortable in power at home, but no safe place for comfortable exile available.