Answer:
Because, governments provide the parameters for everyday behavior for citizens, protect them from outside interference, and often provide for their well-being and happiness. In the last few centuries, some economists and thinkers have advocated government control over some aspects of the economy.
Governments provide the legal and social framework, maintain competition, provide public goods and services, redistribute income, correct for externalities, and stabilize the economy. ... Over time, as our society and economy have changed, government activities within each of these functions have expanded.
