Hume thought hereditary monarchies have non-violent transitions in comparison to non-hereditary. Yet we know from reading Shakespeare and the history of Byzantium that is not so.
Hume assumes the Roman Republic was a democracy that didn’t work as the plebes in cities ran it to ruin. If one reads Livy one learns about the Roman Senate and its power as well as that of the consuls and master of the horse during war. Those were not powerless people. The plebes never came in to their own until they demanded Caesar have power, then they made his emperor. I believe Hume’s Roman analysis is very poor.
Hume believes that monarchs treat provinces better than democracies. It is strange that he overlooked America in his analysis. King George III was the reason for the rebellion. The U.S. government sometimes has treated its ‘provinces’ or territories better than the states. Puerto Rico received billions and billions for hurricane relief in 2017-18 for example. I think Hume realized who buttered his bread in the England of his day- the nobles. Maybe they should have been named something else such as power goons level I, II III etc.
Spanish monarchs allowed slavery in Latin America as did England in what became the U.S.A. Slavery was brought to half the world in fairly modern times thanks to monarchy. About 16 million aboriginal Americans perished during the era of Spanish royal power. it wasn’t a pretty time.
Hume use the term “government after the eastern manner” a couple of times. That might have been a bete noir of the time. Oriental despotism was a cliche. The Chinese imperial court was terribly lax. It was apparently quite authoritarian at times as was I suppose the Tokugawa Shogunate in Japan.
Hume posits various pure forms of government (three forms actually) and describes them as strong or mild versions and considers them in a mildly Aristotelian (the Politics) way, ineffectively. I agree with Hume’s method of existential historical analysis yet he needs better though about human social organization. There are an infinite number of possible forms of human social organizations; well, at least as many forms as their are configurations of pieces on a chess board. The goal is to make the pieces work well together, and to assure that all the pieces have equal rights of value though some are more powerful than others. Human for some cause lacked the insights provide by the mathematical concept of Hilbert space permutations applied to political structures and ideal ways of responding to emergent issues, such as is possible today.