Actually, the government is the only thing keep corporations in check. That's because government control is not the only way that organizations can influence individuals, economic control is another method. Just look back at American history, and you'll see what happens when the government fails to regulate corporations (and work environments in general). We used to have almost no labor laws, where workers were forced to work 12-15 hour work days, seven days a week, in dangerous and difficult work environments. They would hire private detectives to defame, threaten, or kill union organizers. Regulation on what went into products was non-existent, as were environmental controls. All of these things have a real impact on people's lives, health, and individual freedom.
Those who don't have independent wealth must have a job in order to survive, and in any economy that is not fully controlled by government (i.e. almost all today), businesses will grow and consolidate until they have a monopoly over a given sector of the economy, unless government provides some sort of check. This includes the labor force, so just finding a different job with better working conditions is not always an option.
To say that individual freedom would be maximized only if the government was greatly curtailed, and corporate power greatly enhanced, can only result from ignorance of history. I'm not one for the overthrow of capitalism or anything, but reasonable limits on corporate power I think is just common sense. I do agree that public influence over government is seriously lacking and needs to be addressed, however.