Autocracies have more variability. There were good kings and bad ones. When the tyrant is smart and genuinely lifelong committed to the good of their people you get the most efficient system. This is the classic argument monarchists have. Problem is in reality the planets alignment rarely happened.

I agree that a good autocrat can be more effective than a democracy, but also think that bad ones are much worse. Plus autocracies are notoriously bad at picking good rulers/successors, so you end up with a lot more poorly run than well run countries.

Is that true? I've heard that the build quality for new houses in China is terrible.

Which autocracies were/are efficient? Were East Germany, the USSR, Mussolini's Italy, or Nazi Germany efficient - not sure they were. They could get certain things done, but that is very different from being efficient (or even effective) in broader sense.