Humans are still generally better than just having a robot there because they're both more flexible and capable of problem solving. Maybe for the same money you

Humans are still generally better than just having a robot there because they're both more flexible and capable of problem solving. Maybe for the same money you could get enough robots there to make up the gap but sending humans to Mars is sexier and attracts more money than you could get for the robot missions. Then even if we never actually go 'preparing' to go to Mars attracts ongoing money for studies on the ISS and for sending robotics missions.