Government literally created the concept of a company. Before any Joe or Jane could create one, they had to be 'chartered' by a government body.
Governments create the rules for a company to follow - they create the dispute resolution mechanisms for companies to follow when they fight with one another (see Chancery Court). Government regulates the conduct of a company, by defining the criminal code for corporations and their officers. Ownership of a government cannot be sold on an open market. There are many distinctions that puts government into a unique class.
Saying that 'Government is a company' is some elementary school logic.
If anything, it would be more technically accurate to say that 'A company is a government - with a very limited set of powers.'