Firstly: I am not a classical historian, but rather a classicist, and so my expertise is more on language than history. Also, I focus more on the Roman side of things than Greek, so any historians or other classicists can feel free to elaborate/correct me here.

For starters, virtually all of Europe is more densely populated than Alabama, which is deceptively large. It wasn’t as easy for people to migrate large distances when Greece was settled, and the mountains helped to ensure that there could be lots of states relatively close by, but who did not interact much. This is partly why sea travel (and naval warfare) became so prominent for the Greeks later on, once we can really call them Greeks.

Next, ‘partial independence’ is tricky to define. We often talk about ancient Greeks as colonizers who would set up client cities in Greece and abroad, such as in Anatolia, Sicily, Southern Italy, or even France. Defining the number of states that were ‘in Greece’ can be tricky if you have a particular idea in mind for Greece, rather than being of Greek culture or heritage.

All of these would have maintained some level of independence, as it took time for news and control to spread. We tend to think of the Greeks as being of one culture, but they saw themselves as wholly and distinctly separate, from local gods to goods produced and festivals. From their perspectives, they all had relatively little in common aside from their language and the games.

I hope this can shed a little light on your question, though it’s far from a comprehensive or thorough answer.