I don't think the "responsibility" part is all that important. There are many points about it that can be argued, but I think the more important part is means.

Private companies' only effective means to do anything are to produce a product that people freely choose to buy and attract people to work for them (absent a few rare exceptions).

Governments have effectively unlimited means to compel people. They can spy on anyone, fine them, throw them in jail, kill them, all for as much and as long as they feel like.