I think I'd have to introduce some kind of penalty for civilian death if they're in a level. It would be a neat visual to see cars driving away at the start though.
Brigador gives you no penalty.
How the story treats civilian deaths is a matter of worldbuilding and intended tone: "We are being sued by 7 IGOs." / "We investigated ourselves and found no wrongdoing." / "The vice director of operations has been detained by the United Kingdom." / "We are billing the province for negligent evacuation as outlined in our ToS." / altered news headlines between missions / a slight variation in the ending / your supervisor being annoyed with you
How the game treats them is essentially a wholly independent design issue: score deduction / score increase / monetary penalty / nothing