That hasn't been the plan for a long time. NASA's Design Reference Mission, and the one anyone who has studied Mars missions at any point in the past 20 years, is to manufacture fuel on Mars. In fact, you would probably send this equipment to Mars first so that the astronauts going to Mars would have a fully fueled return ship ready and waiting for them before they even take off from Earth.
The only problem with that is we would have to get a lot better at building rockets first. Currently it seems to take a fairly large crew (and clean rooms and a lot of care) to get a successful launch off earth, and even then there are often glitches. Getting the Moon lander to launch from the moon surface was easier due to lower gravity and no atmosphere. But I can't imagine a rocket on Mars sitting there for a couple years with an automatic fueling station, and having it launch successfully after getting battered by dust storms and any other corrosives present on Mars.
That hasn't been the plan for a long time. NASA's Design Reference Mission, and the one anyone who has studied Mars missions at any point in the past 20 years, is to manufacture fuel on Mars. In fact, you would probably send this equipment to Mars first so that the astronauts going to Mars would have a fully fueled return ship ready and waiting for them before they even take off from Earth.