Who owns the public space

A public space is a dynamic system and changes every day, so it should be a space to make live worth living.
In the 70is and 80is there was a liberal handling of using the public space but today things are differently. 
Nowadays many times the usage of public space is not free anymore and house rules predominate our everyday lives.
You will find alterations, like privatization of public space, for example Shopping Centers are privat but still open. 
Instead of exluding human beings we should find a right way to share our space.