Governments are monopolies because there is only one per country.
Governments have a secure income from their citizens and do not need to improve. But like so many monopolistic enterprises driven by vested interests, they create inefficiencies costly to society. Similarly, changing the politicians after several years does not improve government, because the vested interests remain the same. People realize that the methods by which they are supposed to be able to control their government are ineffective. We experience problems every day when monopolies rule our lives.