If you include the retired and the children in that number, then it becomes possible, but in that case I argue that you're presenting the numbers in such a specific way just to make them agree with your opinion. Because then the fact that 50% pays no income tax has absolutely nothing to do with whatever form of government is in place.
If you include only the number of people who are expected to bring in a paycheck vs the people who actually do, the numbers will not be close to 50%. Not even remotely.