When people are not limited by government, they do better for themselves and the nation. Why then do so many turn to government when it consistently fails to perform better than the private sector in most categories?
The answer depends on how you define your options. For Thomas's purposes, turning to the private sector rather than government is equivalent to "do[ing] better for themselves and the nation." In other words, the choice between private and public sector is equivalent to a choice between self-reliance and dependence upon government. However, many of the "so many" don't see it that way. For them, turning to the private sector isn't opting for self-reliance, but subjecting themselves to bosses on pretty unilateral terms. They somewhat understandably see turning to democratically elected government as a form of empowerment rather than as a way of limiting themselves. They see government as their instrument for bettering their lives. That it sometimes (or often, if not "consistently") doesn't work that way doesn't prove that it shouldn't. A democratic ideal of government would seem to presume otherwise.
The next question would be why people like Cal Thomas don't see government that way. Why don't they see a democratically-founded government as an instrument for improving their own and everyone else's lives? A number of answers are possible. If Thomas were a conservative in the philosophically pessimistic mode, he might answer that we can't depend on government to improve our lives because it's liable to failure. In a more moralistic (and more likely) mode, Thomas might say that government can only make some people's lives better by making other people's lives worse -- it can only provide benefits to the needy by taking from (i.e. "punishing") the successful or the self-reliant. American right-wingers, as a rule, don't believe that government has a moral mandate to do this. The natural corollary is that people have no right to use government for that purpose. To date, Republicans have had only limited success convincing the public of this.
The Republican and liberal worldviews are like mirror universes. One side's empowerment is subjection and dependence to the other, and the other's self-reliance too often looks like subjection and dependence to the one. I'm not sure if either side can objectively refute the other, since there remains, in theory, a self-reliant alternative to democratic "co-dependent" empowerment, and it remains possible, from a holistic perspective, to challenge the entire notion of human self-reliance. But absolute agreement isn't necessary in a democratic republic. So long as people's constitutional rights aren't violated -- and nothing in the Constitution exempts citizens absolutely from contributing to the public good -- all we need is for a voting majority to agree on one point of view, and for intellectual minorities to defer to the majority will (while exercising their prerogative to protest) until the next election. To sum up, we don't need to convince Cal Thomas that it's right (or simply our right) to turn to government. All we need to do is outvote him and his side.