The trolley problem was never about the trolley
The philosopher who invented it wasn't testing your instincts about trains. She was arguing about something far more contested.
Everyone knows the setup: a runaway trolley, five people tied to the track, a lever that diverts it onto a side track where it kills one person instead. Pull it or don't? The scenario has become a kind of moral Rorschach test, repeated in ethics classes and self-driving-car debates and a hundred internet memes about pulling levers.
Philippa Foot introduced it in 1967, and she wasn't trying to build a lever-pulling thought experiment for its own sake. She was trying to defend something called the doctrine of double effect — the idea that there's a real moral difference between causing harm as a means to a good end and merely allowing harm as a side effect of pursuing one. Her actual subject was abortion, and specifically the debate over whether it's permissible to save a mother's life by an act that kills the fetus as an unavoidable side effect, versus one that kills it directly as the method. The trolley was a clean, bloodless way to isolate that distinction from the emotional weight of the real case.
It was Judith Jarvis Thomson, writing nine years later, who renamed it "the trolley problem," multiplied its variants, and effectively detached it from Foot's original argument for good. The train has been running on its own track ever since, decoupled from the question it was built to answer.
The puzzle everyone argues about is a stand-in that outgrew its original case. The real argument — what we owe to outcomes we merely permit versus outcomes we actively cause — is still sitting where Foot left it, mostly unattended.