There is a good Milton Friedman video wherein he explains why tax reform won't happen in the United States. The key is that the ideal goals of a tax system (e.g. generate lots of revenue with little inefficiency and little impact on taxpayers' personal financial situation and few unequally distributed loopholes like corporate tax avoidance) are not the goals of lawmakers who define the tax system.
In the video, he focuses on a theoretical tax system just like our current progressive income tax, but with all brackets >25% limited to 25%, and argues that it would be an improvement (according to ideal goals). But I think the argument could be extended to basic income or negative income tax, the latter of which Friedman also advocated.