Getting my sci-fi hat on here but, it would in theory be easier for them to pool their money together and buy / build their own spaceship. Of course, this assumes that each ship is its own political entity; in practice, we'll probably see the equivalent of countries and states but in space, spanning territories and jurisdictions that span multiple habitats.
Why would separate spheres be any better than counties. One of the things that shot us up is the industrial revolution and that was mostly powered by cheap trade routes by land and ship.
As in trade is very essential for growth. Both of goods and ideas.
That relies on the assumption that people within a single habitat wouldn't want to separate for whatever reason. Nation within a nation. It already happens on Earth(see: Catalonia, Taiwan, Hong-Kong, Silesia).