Simple: we have no manned Mars program
and further, we have not had one since the last one was cancelled in 1965.
If the majority of the population gave a high priority to sending men to Mars, then we'd have one.
They don't, and barring the discovery on Mars of artifacts of intelligent manufacure, they won't. They are completely satisfied with robot results, and their desire to send men there drops after each robot returns more images of Mars' bleak surface.
bye,
ep