Whether it's rational or not, I'm going to spend less time awake at night for the rest of my life worrying about the multiple people I allowed to get run over by a train than I'm gonna spend worrying about the one person I actively caused to get run over by a train.
Come to think of it, I suppose that heavily discounting the possibility of future regret is also something that drunk people tend to do.
Why would I be sitting in front of that switch? Do I actually know for sure that flipping that switch will have the described outcome? If I'm some sort of passerby who happens to be there, then I certainly wouldn't know that for sure, and I would just be futzing around with railway operations I'm not trained to engage in. I could make matters worse! So it's probably better to leave the switch alone rather than potentially causing even more harm. Try to yell at the people on the tracks to get out of the way, and call it a day.
If you do know operations, and you are at the right place operating machinery you're trained to do; then part of your training may have involved how to deal with this hypothetical situation. So it's probably best to keep on your railway operations hat and defer to your training, rather than putting on your philosopher's hat and think deeply about the implications of your actions.
More formally there's two cultural issues that the philosophers more or less refuse to deal with and instead claim inherent biological instinct or whatever.
One is we've been indoctrinated for better or worse with a deference toward specialists via all kinds of morality tales and drama. You shouldn't tell a doctor how to doctor, or a laborer how to labor, according to a zillion dramatic morality tales. Its deeply hardwired into the culture itself. Therefore its culturally wrong to mess with a railway workers switchgear unless you're a railway worker, which you probably are not. You can daydream all you want about possibly knowing how to operate railroad gear, but according to doctrine if you were a railworker, you're supposed to be pretty pissed off if some random member of the general public disrespects your entire field of employment by flipping switches. No matter your real or theoretical employment, we're indoctrinated to leave those switches alone.
The next deeply indoctrinated belief is people are conservative about what they know best. Obviously you know nothing about railway operations, or at least less than the guy assigned to operate that switch. Clearly someone who knows what they're doing set the switch that way for a reason, so if I operate that switch I'm almost certain to be doing something wrong because the guy assigned to it felt he was doing right. In part two of the classic telling, clearly the fat guy knows he's not fat enough to stop the train by lying on the tracks so he didn't jump on them by himself therefore pushing him on the tracks is just going to increase the death toll. The only people who want to upend the cart are actual experts, arrogant, or insane, at least according to cultural myth.
Its possibly in a different culture we'd get totally different results. Maybe in a video game where its "make believe" and not in our culture, you'd get different results. Someone should try these scenarios in minecraft and then compare/contrast results.
But no one wants to do anything because any wrong that happens will then be blamed on them. So if there are 10 issues a day caused by bad policy, and you can change it to only be 5 incidents a day, no one is going to push for changing it because then they would be viewed as responsible for the 5 incidents instead of being viewed as reducing the incident count by 5.
You pull the switch to kill one to save 5, you have now directly acted to kill a person. You are a killer, and while perhaps not legally a murderer, some will still view you as such. That you save 5 is irrelevant.
To see an even strong example of this behavior, consider some action that is even more offensive to the common sensibilities that killing someone, such as certain forms of child abuse. Now imagine a situation where by doing that to one child, you can stop it being done to N others. (Worry not about the details of how such a situations could occur, I'm sure some creative individual could find a back story.)
Now imagine how someone who chooses the utilitarian choice is going to be viewed. Perhaps we should be doing tests not about what the subject would choose, but about how the subject would view another's choices.
Use this thing: http://www.scp-wiki.net/scp-231
Imagine you're an accountant working for the government. You choose how medical research funds are spent. One day, you notice that there are two equally expensive programs: Program A, which will save one life next year, and Program B, which could save five lives next year.
Program A is being funded, but Program B isn't. Program B could be funded if you took all of the funding from program A and diverted it.
Do you divert the funds?
Distilling real-life into utilitarianism scenarios is fraught with reductionism - there are many factors that drive people's decisions and those all add up.
For me, it depends on the chances of "could save five lives" and the cost of the program.
If the chance of "could save 5" is under 20%, no, you don't divert the funds.
If the total expense of the program is over some threshold per life saved, and there is another opportunity, C, elsewhere to expend those funds with a better outcome (more lives saved/extended/improved), you defund both A & B in favor of that other program.
If you're e.g. making a change to road signage, you wouldn't start out with the total number of KSIs, you'd be looking at the potential reduction in KSIs. Similarly, if you're looking at a medical intervention, you'd be measuring a probability-adjusted delta in QALYs (in the UK).
The question specifically used certain language for one branch and uncertain language for the other, so I replied to the question as asked rather than strawmanning an answer to a question that wasn't asked.
s/could/would/ would have eliminated the ambiguous reading.
That is exactly consequentialist thinking, though. Choosing your actions based on social signalling in life-or-death situations is a really bad idea.
You get promoted - You celebrate by going to a bar to have a few shots
Your favorite basketball team wins a match - you celebrate by getting hammered
Most people don't drink to shut down emotions, however.
Some other people enjoy the socialization places like bars and whatnot have.
You don't want to flip the trolley switch in part because you feel more likely to be blamed for the outcome, or to be held accountable for making the wrong decision. After drinking a bit of alcohol, it is easier to forget about how others will perceive your actions and instead think about the physical consequences of the actions themselves.