I struggle to imagine any situation where that’s the only two options.

Alright, I’ll take this in good faith. Here’s how that happens:

Speeding.

As we all know here, speeding makes crashes way worse, and it makes the braking function fail proportionally.

So, imagine:

The killer road bot is speeding through a street. It’s a bit narrow, there are cars parked illegally on the sides.

The killer road bot enters an intersection and makes a left turn with speed and a there’s someone on a crosswalk.

The killer road bot controls at least these aspects of the car: brakes, acceleration, steering. The brakes can be engaged, but the speed makes them useless in preventing running over the person on the crosswalk. The acceleration is not useful. Everything is happening too fast really, and the killer road bot can’t even calculate which direction the person is walking in on the crosswalk.

The only useful control left is direction by steering. The killer road bot thus has these choices:

1. Maintain course, run over person on crosswalk
2. Change course

Choice 1 leads to the obvious outcome.

Choice 2 branches out:

2.1. Turn left

2.2. Turn right

If the killer road bot turns left (2.1), it flips the car over and sends it rolling into other cars, thus endangering the passenger(s).

If the killed road bot turns right (2.2), it hits a large tree.

These are the only options.

edit: typo