Well they must not be making a profit, for one. Another reason might be that the corporation is paying one before the other, example, pays 28% to taxes, leaving 72% left, and 95% of that 72% gets taken, leaving the corporation with ~4% of their total profit.
Another thing may be that you are not in control of these corporations. If they were State Corporations you might not be having this problem. Check if the corporations are Private or Public Corporations.
However, I do have to ask, are you sure that they are not paying taxes/profit share? I mean check your country's monthly budget, and/or check the corporations cash flow table, if its paying taxes, it will be listed.
Hope this helped.