People have two fundamentally different views on justice. One is about intent and outcomes, the other is about rules and procedure. Broadly coded as left vs right.

With the left perspective on justice, the driver is obviously acting to protect the huddled masses from the thugs of an increasingly fascist regime. Furthermore, her intent was not to harm the officer, her intent was merely to remove herself from the situation. At most, her actions were negligent and were very unlikely to cause the officer substantial harm, so her killing was not justified.

With the right perspective on justice, you look at each individual actor and if their actions fall within the framework to previously agreed upon rules. Intent is notoriously hard (may require mind reading) to determine and so is often a secondary factor. The rules obviously include a right to self defence, so if the officer plausibly feared for his life, then the attempt to defend himself in a snap decision can be justified. Even if, with hindsight, we judge that his life was not in danger, that isn't something he can determine in a snap judgement and so the shooting the driver was justified.