What about Qatar, Saudi Arabia, and more notably Russia and China? I don't think any of them qualify as poor and struggling?
Also, causation and correlation. Poverty might be related to authoritarian, but not necessarily caused by it. For example, many counties are poor because of colonialism and the political vacuum left over when they gained independence.
In addition, looking at stats in this way is prone to sampling bias. If you take a look at the list of non authoritarian counties, many of them might not be necessarily doing better.
It's almost as if authoritarian rule was inefficient and wasteful in resources due to having to spend most of its energy staying in power and favoring corruption and political favoritism at the expense of good policies. Sure you may offset that with incredible amounts of natural resources (oil and large territory) but inequality does not go away. Also, sooner or later natural resources run out.
There are some good arguments for why it might be the cause of it. A book I really enjoyed on this subject is called "The Dictator's Handbook".
One of the arguments in the book is that in dictatorships, the rulers have much less need to please ordinary people, and they are better off utilizing their available resources to enrich themselves and buy loyalty from other powerful players. If they are not able to gain loyalty from other powerful players they risk a coup. Where as in democratic societies, the leaders need to please the people, otherwise they risk losing power by being voted out.
A reasonable explanation for the few authoritarian counties that do not have poor and struggling populations is that they have an outside player that is threatening them. In these cases, they have demands for something more than what they can bully out of their populations. So you are going to see widespread education, and ideally, prosperity. This gives them advanced military technology and economic power.
I am likely doing the book injustice in my representation of it, but it is able to provide a very solid argument for the above being true. Both from an analytical perspective, as well as a historical one.
In the most strict definition of poor (living under 1.90USD a day), only 0.7% of Chinese are poor. Even if you go up to 3.20USD per day, it's still only 7%, way less than billion.
https://en.m.wikipedia.org/wiki/List_of_countries_by_percent...