But she says the Tesla didn't brake at all, which suggests it just didn't recognize the deer or doesn't have a rule saying that an animal walking toward the road might be dangerous.
By your logic, one needs to move 30mph on the interstate to make sure they can react to whatever jumps out at them. Or am I misunderstanding something here?
I've encountered many situations like this without hitting the animal. I would slow down and move aside to give the deer room, starting as soon as I saw the deer at 3:53. If the deer had moved faster and taken the whole lane I'd have passed it in the other lane. The oncoming car wasn't that close.
But you must also be able to stop in this distance, because the obstacle might not be a deer you can steer around, it might be a fallen tree that blocks the whole road.
You're certainly right that many human drivers would not do better than the Tesla here, but we should expect the Tesla to be better than a bad human driver.
The speed limit is supposed to be the maximum appropriate speed in ideal conditions. In practice almost no one treats it that way, but that's the philosophy by which it was designed. They take into account the clear area on the side of the road, sight lines, and the curve of the road itself.