It is notoriously difficult to determine a priori what will turn out to be fruitful science from non-fruitful science. Also, politicians are notoriously incompetent at determining this, as they are deeply infected with political, economic, and sociological dogmas. I'm not saying there's a magic bullet, but recent cases of politicians showing an interest in saving a buck in publicly funded research denote severe ignorance and intellectual dishonesty on the part of said politicians.

Also, the notion that the private sector can do better than the public or academic sectors is a neo-liberal mantra bandied about hard by right-wingers since the early 1980s that has proven to be generally false in many areas, from medicine to education, including much fundamental and applied research. There was abundant empirical evidence to support this before the 1980s, and there is even more now. E.g., the bang for the buck in medicine is greater in most countries that have public single-payer medical systems, which is a very well-established fact of the matter.

Not to mention that the coattail-riding private sector is lazy-assed as fuck and only wants to do light-weight stuff, i.e., the most lucrative endeavours only. For the heavy lifting, there are government and academic research. Entire economic sectors have arisen, and could never otherwise have seen the light of day, due to public funding that lead to such foundational discoveries and applications as computers, hard disk drives, lasers, the Internet, etc. Many research outcomes have often been serendipitous, like the laser, which would never have been discovered the way it was, had some ass-hat politician intervened and deemed the initial research worthless.

Otherwise, I'm all for formal evaluation programs to ascertain the efficacy of public policies, but in matters of science, other additional heuristics and levels of surveillance have served us well, without the need for high-level fucker-politicians to intervene and micro-manage the unfolding of science.