One thing bothers me a lot is, if government organizations can be influenced by lobby groups, which primarily owned by corporations, then why do we need government?

Corporations and governments should be considered as balancing forces, one works to increase its profits by any means, other works to protect humans living in that area by any means.

You might say, corporations benefit its employees, true, but it is a small subset of people living in the country. If you allow everything to corporations, they will set up a slavery system from the birth of a baby

Lobbying having undue influence is entirely a government problem that it needs to fix. It will never be fixed while people have the attitude that lobbyists are the problem. (I'm not saying you're saying this; just making a statement.)