Dive into your creative stream
Sky city and its people are a perfect example of how a lack of curiosity results in a lack of understanding. And sometimes a lack of understanding breeds fear is some and leaves dictatorship a very plausible possibility.
Personally, I believe that Isa never truly meant to be a dictator and that her primary reason for imposing the rigid rules that she did was to ensure the stability of the city and the safety of its people. However there is no denying that she benefited from her people's lack.
She owns the Eversource. The one her people don't have, she does and that is an abundance of natural resources. It's all at her disposal so this automatically places her at the top. What maintains her position at the top is the fact that the majority of Sky City people have to rely on her to provide them with the means to build. They simply cannot just go off and build as they please and flourish within their own little communities.
So now not only does Isa have an abundance of resources but the Sky CIty people have to rely on her for these resources.
She has made herself the only source that these people have and they can't do anything about it because they don't have the means to. Isa can now make rules, give and take as she pleases all without having to explain herself to her people because they are afraid of her.