These governments activites are examples of

Collecting tax, borrowing money and establishing courts are government activities are example of reserved powers.

This kind of power is not restricted or given by law or any organ of the government. In different countries, the reserved powers are given to different branches.

For example, in Canada, the federal government holds the reserved power while in the United States, constituent states possess reserved power. While countries like India, Israel, Ireland whose legal framework are similar, have same status and framework of reserved powers.

a social contract.

"a social contract is an agreement between citizens and their leader where the citizens give up certain freedoms in exchange for protection. the constitution of the united states is an example of a social contract."