The programmers are of course aware that there is more than one conception of what constitutes a moral decision, so they're crowd-sourcing their morality in the hope of creating different driving strategies according to the cultural priorities of different countries. If you click on the link above, you can add to their database.
Anyway, I was very interested to read this article, which crunches some of their data to show how priorities differ in different countries. For example, should the self-driving car choose to run over young people or old people?
Far-eastern countries, perhaps under Confucian influence, are much more careful of the lives of the elderly, whereas the West is in general keener to preserve the lives of the young - perhaps on the individualistic principle that older people have already "had their turn". The data doesn't give us explanations, but such graphs are of course an open invitation to draw on national stereotypes.
What about the importance of sparing more lives rather than fewer?
Again, there's largely an East-West split, with Westerners perhaps performing a kind of utilitarian calculus whereby three lives are worth three times as much as one. This doesn't mean of course that Japanese drivers will recklessly swerve into crowds, merely that they place less emphasis on numbers.
The one that interested me most was this one, concerned with whether one should spare pedestrians or passengers:
Here, suddenly, China and Japan are at opposite extremes, and how! Chinese drivers see random pedestrians as far more expendable than the friends, family or colleagues who are presumably their passengers. (Note to self: look both ways on the streets of Shanghai.) Japan, by contrast, sacrifices passengers to pedestrians to a very marked extent.
The obvious explanation, it seems to me, lies in the uchi-soto (inside-outside) principle, which demands that outsiders be treated with preferential politeness and consideration. The nature of the in-group depends on context: it could be one's family, one's school, one's company. When referring to members of one's in-group to an outsider, you always use humble language; when referring to outsiders, you always use polite language. For example, if I want to mention my son, I say "musuko", but your son would be "musuko-san". If I'm the humblest employee at Sony, then I will refer to my CEO as Yoshida, without any honorific, when speaking to people outside the company. (Inside the company, it would be a very different matter.)
Perhaps, for the purpose of the MIT experiment, passengers are regarded as "uchi", and pedestrians as "soto"? That's just a top-of-the-head theory, but I find it plausible.