I've found a good rule of thumb for complications is that projects that are governed by the law of the universe (e.g. chemistry, physics) might be super hard, a

I've found a good rule of thumb for complications is that projects that are governed by the law of the universe (e.g. chemistry, physics) might be super hard, at least the answer will probably be a widely agreed to pass / fail (e.g. the rocket guidance worked and the rocket did not blow up). On the other hand, software defined by bureaucrats (e.g. payroll, regulation compliance) is going to be complicated with loopholes and journeys into minutia and logic defying requirements. Its all head space with very little logical basis. Everyone has an opinion and its all probably valid, or at least the invalid is disguised fairly well.