It is a government without infrastructure. In the United States, for example the National Government has certain powers and the 50 states have others.
This is a system which people choose their leaders directly or indirectly by voting. Unitary systems increase efficiencies by reducing bureaucracy. In most governments with this system, the power of making a decision lies with one legislative unit or even just one person.
List and explain the five basic functions common to national governments throughout the world. Everything is centralized within a unitary system, including financial decisions. It is a government which ignores local issues. That reduces many of the problems which are associated with this form of government because it provides a certain level of infrastructure that can be used.
That means the decisions affect local communities without seeking out their advice to determine what their needs may be. Because power rests centrally within a unitary system, there are fewer delays involved in the processing of a decision.
Because there is a large amount of power, often political, that is invested into a unitary system, this form of government is one of the most likely that leads to tyranny. It is a government in which all powers held by the government belong to a single, central agency.