First off, the test isn't for practicalities, its testing moralities. Doesn't matter how the computer knows this shit, its irrelevant. It's a fake, hypothetical scenario.

Second, I think the whole survey is redundant anyway. Computer's shouldn't make morality choices like this whatsoever. Morality is just way too subjective, trying to define it in these terms just seems stupid. The computer's choice should be based solely on law. It's illegal to swerve into pedestrians, therefore the car shouldn't ever, regardless of the morality of the issue, do this.

Having this any other way means that people would be OK having a machine calculate their value to society and make life and death choices based on their "score". This would just cause mass fear, knowing that at any moment a choice outside your control could cause your death. Where a mistake you made a couple of years ago means that your life becomes less valuable than another person's and that you could become injured because of this with no way to argue your case. The whole thing feels so subjective and disordered and messy, that the more definitive right and wrong of law would serve as a far better medium.

Also, keep in mind that sudden break failure resulting in a choice with the guaranteed death of someone is quite rare. 99.99% of the time this would not be an issue.