I think one of the primary ideological motivations for treating governments and companies differently is to optimize freedoms. An action by a government has the ability to negatively affect millions of people who lack meaningful alternatives. By contrast until very recently any given action by a company could negatively affect the "freedoms" of an extremely small section of society, and there would generally be plentiful alternatives available. The only exceptions being in things like cartels, which is why we passed laws making such illegal. So optimizing for the freedoms of companies, and limiting those of governments, increases the overall freedom within a society, instead of reducing it.
But today while the actions of governments can negatively affect millions leaving them with minimal realistic alternatives, the actions of a handful of companies can negatively affect the freedoms of billions leaving them with minimal realistic alternatives. This is a scenario that's never really existed in humanity in a meaningfully similar way (the problems of e.g. Standard Oil or The East India Trading Company were quite different), and so we have no precedent or words of wisdom to guide us - we're on our own.