None of the information I've seen posted for alternate tax systems by conservatives / GOP have ever had anything like that. That is something I hear a lot from papers that lean left, but is not the reality of any of the plans. Even the sales tax-based plans take great pains to make it easy on lower income folks. I just see it as more bad math.
I don't believe politicians will change the tax system because it is a powerful tool to impose their will and gain campaign contributions. Its a basic self-interest thing which explains the majority of politics.