'railroading' is not primarily used as a metaphor, it's used as terminology, but in the metaphor that represents the terminology, the tracks only go to one location, through one pre-established route, with no deviations or branching paths allowed for the players on the train, saying 'the players can choose to take the railroad many places' is a bit of an oxymoronic statement as the railroad doesn't have many destinations or routes, it has one: where the GM decides it goes.
Exactly.
If
@Celebrim would prefer it, think of "railroad" as meaning an on-rail public transit system, such as Chicago's "L" trains.
Passengers do not get a choice about:
- when trains arrive. They appear when they appear.
- where a given train goes. It follows a planned route.
- where they disembark. Stations are fixed places.
- how frequently trains arrive. The number of cars is set.
That is what "railroad" is referring to. This, then, in contrast to driving, biking, or walking, where--up to the limit of
safety and
legality, which are pre-existing obligations and thus not impinging on any freedoms, assuming the laws are reasonable--the driver/cyclist/pedestrian has full control over all of the above. You decide when to depart, where you go, where you disembark, and how frequently you travel.
That is what railroading communicates. You are on rails. You do not get to go anywhere other than where the train is going. If, by sheer coincidence, you
only ever want to go to train stations, then awesome! But it is
exceedingly unlikely that ALL you ever want to do is visit (say) London underground stations. It is much more likely that you want to visit places that you can
reach from said stations. And, therefore, it's also much more likely that there can be friction because you'd prefer a stop closer to where you want to go.
GMs desiring to have fun and to run a campaign they're interested in running are not railroading
solely for those reasons. That, in fact, is one of the biggest benefits of a "session 0"; it helps you tell your players what
you want to do, so they can make an informed decision about participating. I, for example, was up-front with my players that I'm not into grimdark $#!+, I think that's the most tedious garbage ever committed to the page--but I do include dark
things in the world. It is a bright world
threatened by darkness...and heroes can be (part of) what prevents or permits that threat to come true.