"Government subsidies are not needed to keep these companies is business"
they technically are, especially employment-wise. barack obama gave general motors a bail-out during his terms while the nation was recovering from secession. if he didn't, gm would crumble and massive layoffs would've happened, especially in detroit.
another thing that these companies do to gain the upper hand is lobbying. lobbying is what airline companies are doing now in order to prevent private railroad companies from building passenger service. back in the '50s-'60s, general motors lobbied eisenhower to build the us interstate highway system while housing companies built suburbs, turning once-liveable, streetcar-using american cities into car-oriented, government dependent hellscapes.
lobbying kills the true free market. bernie sanders wants to halt the corruption in washington dc and provide future for profitable business ventures. this has not been done by the last 4+ presidents, which is why the people want bernie.