The incident in Kabul is the cost of doing business in war and security operations. The military understands that but politicians and the public do not or at least act as if they don't.
Civilized people have decided that the costs of war are too high (which is why the US was leaving, it turns out); dismissing clear and unforced errors as "the cost of doing business" is a diffusion of responsibility and obscures causal relationships with a handwave.
Individual people made unforced decisions to slaughter children that day, and other individual people made decisions to cover it up and protect those who made the first error. The New York Times then blew the lid off of it and made the efforts of the second group ineffective.
In my own personal opinion, all of the people in this criminal conspiracy should suffer the absolute maximum penalties allowed by law for conspiracy to commit premeditated mass murder. This is not just "the costs of war"; there was no threat whatsoever. The costs of war also do not justify post hoc deceit to cover one's ass.
