Your point about Turkey and Saudi Arabia is valid.

Alliance with Saudi Arabia is realpolitik at its worst, although you could defend it by saying that they have never had democracy, and while things don't get worse then there is no impetus for sanctions.

Turkey is a much more apt comparison. That is another democracy sliding into dictatorship, although slower than Venezuela. To be clear: western governments have kept their mouths shut because Turkey is a key member of NATO, not because of any economic or political ideology. Putting geopolitical concerns over principles is shameful; we should be talking about Erdogan the same way we are talking about Maduro.

Swinging the subject back to US interference is a non sequitor. The US has a deplorable history of illicit interference in Latin America, but it isn't especially relevant to what is happening right now. The current calamity in Venezuela, and Maduro's authoritarian response to it, are of Venezuelan origin.