The results of that study seem to be a bit more complicated in that they suggest that part of the cause of the distinction is that there's a common belief in the population that is very close to witchcraft (where intending harm or desiring can cause harm) and thus intent matters as much as action and there's isn't a clear dividing line between the two.

A rather ironic take on Hauser's Trolley Problem.

These "act" trolley problems have the same difficulty as the original.

It's so implausible that the only way to stop a runaway truck/trolley would be to make it run over a person, that one doesn't know if one's intuition is reacting against the sheer implausibility or the moral dimension.

IMO, telling the subject that "pushing the fat man is the only way" is not helpful. We can't imagine ourselves in that epistemic position.

The best "fat man" scenario is the Unwilling Transplant Donor, but sadly it does not have a good omission counterpart.