It can far more often than not. However certain parties have a vested interest in pushing the narrative that all news is equally fake and that any attempt to distinguish truth from lies is simply propaganda.
It's epistemology 101. Absolute truth can never be determined. So we must inherently use imperfect method of approximating the truth. Those approximations are open to criticism, so any system that determines fake news will necessarily have to take a 'stance' in some situations: it will politicize and reflect the biases of those administrating the system.
