Not being able to collect taxes in regions other than the Capitol City is a major logic flaw in this game. It still costs simoleons to build services in the regions, but they don't contribute to the earning of simoleons.
My suggestion is to build regional city halls that collect regional taxes specific to each region.
Additionally, a new banking service should be created, with a central banking service in the Capitol City that allows for the conversion of different regional simoleons to basic simoleons.
Otherwise, there really is no incentive to open up regions, other than curiosity. Once that curiosity has been answered, regions are just a drain on the Capitol City.
