That's because he who counts the votes, controls the election; and He who decides what counts as evidence (or its weight) controls the empirical truth. all scientific conclusions are at least some degree theory-laden.

Then we get to the fact that scientific truth is not a priori for individuals, it must be communicated from a specific community which, if not at least self-motivated itself (as are most human groups) will be filtered through various political layers; The more privileged that community is (wrt exclusively wielding the power of truth), the more 3rd parties will interfere to acquire it.

This is why political principles exist as well as impossibly ideal empirical ones; The issue is less about the complex issue of objective truth, and more about the autonomy of individuals to choose their own actions, whatever beliefs may motivate it.