As an example: if we agree that the goal of our species is to live for as long as possible and we look specifically at the threat of climate change, then based on that goal, we could immediately identify whether any given economic activity is good or bad based on its effects on the environment, which would be based on empirical data.
Some people may deny the truthfulness of the data (which then creates “climate change deniers”), but at the core of the people who disagree isn’t so much about doubting the facts, but really, they just disagree that the goal of our species is to survive for as long as possible, and it’s likely that they believe that our goal is to use up as much of the earth as possible within every single person’s lifetime.
This seems like standard rational empiricism? Employing reason and observation to benchmark things against predefined values. The difficulty of course is in determining those values in the first place.
For example, if we define 'survive as long as possible' as having 1+ humans alive, we might decide we should kill 1/2 of the population (Thanos did nothing wrong).
The true difficulty with utilitarianism is properly defining the metric to be optimized.