Reasons why we need government, even in a market economy, include:

A. property rights need to be protected to serve as an incentive for innovation.
B. the invisible hand is not perfect.these are all reasons we need a government in a market economy.
C. the market may sometimes fail to allocate resources properly.
D. all of the above

If no police existed, then who would control crime, or at least try to? If no government entity existed to enforce patents, copyrights, etc., no one would be able to do it? The law of the jungle principle would prevail and the strongest ones would take away the ideas and properties of the weaker ones.

The invisible hand is never perfect, never has been perfect and never will be perfect. Those who proposed the laissez faire doctrine a couple of centuries ago, agreed that the economically weak should be left to die on their own. Luckily economists didn't propose that theory, french doctors did. I guess they forgot about their hippocratic oath.

Governments are not perfect, no human being is, and no human creation will be perfect. But at least we live in a democracy that allows us to change our old bad leaders for new bad leaders every four years. Society needs leadership, businesses and markets need leadership.