Why did local southern governments use literacy tests and poll taxes?

This was used to try and limit the voting to the wealthy white man and to not allow poor or blacks to vote in elections.  this way the power would stay in the hands of the rich 

True. you know, tools like shovels.

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.