That's absolutely true, but I think the hesitancy about sending humans to Mars is that it is such a desert, and so the payoff will be quite limited to most people besides geologists. From the point of view of the general public, it's cool that its on another planet and we could do interesting science, but realistically it doesn't seem worth colonizing.

This is one reason that Europa excites the public imagination despite the hideous problems of distance and proximity to a gas giant - that moon appears to have a thick crust of ice covering a liquid ocean, and thus the prospect of life - possibly alien life, possibly a means of maintaining human life.

If we found evidence of life, even fairly primitive life, there would be plenty of money and public support to study it (though not without controversy). Rocks and canyons, not so much.