Learn Spanish (Latin America): Ojalá el evaluador no hubiera mirado el retrovisor. - I wish the evaluator had not looked in the rearview mirror.

Because this is an unfulfillable wish about the past. The evaluator already looked in the mirror, and we are wishing that past event hadn't happened. To express "I wish [something had/hadn't happened]", we use ojalá with the past perfect subjunctive (hubiera + past participle). If we were wishing for something right now ("I wish he weren't looking"), we'd use the imperfect subjunctive (mirara).

Could I say hubiese mirado instead of hubiera mirado?

Yes! Both are correct forms of the past perfect subjunctive. In Latin America, the -ra form (hubiera) is much more commonly used in everyday speech, but you will definitely still hear or read the -se form (hubiese). They mean exactly the same thing.

Does ojalá specifically mean "I wish"? How would I say "She wishes the evaluator hadn't looked"?

Ojalá doesn't actually contain a subject; it originally comes from an Arabic phrase meaning "God willing." It essentially translates to "If only..." and sets a wishful mood for the whole sentence. If you need to specify exactly who is doing the wishing, you would drop ojalá and use a conjugated verb like desear (e.g., Ella desea que el evaluador no hubiera mirado...).

Why is there no preposition? In English we say "looked IN the rearview mirror."