It is easy to think that a human on Mars would be much more flexible when you look at the current robotic missions. But they don't give a fair comparison. The main problem isn't the robot, it's the time delay sending signals to Mars.

Opportunity took ten years to travel as far as the early Lunokhod 2  rover operated remotely from Russia did on the Moon in about four` months.

It's much worse than the time delay of the light speed travel to Mars would suggest. Because we have low bandwidth connections and only communicate once a day typically. If the rovers were on Pluto, it would make almost no difference to the time it takes to explore.

So, before you can make a proper comparison, first we have to increase the bandwidth for communications to Mars. A human mission would have broadband - well why wait for humans? Set up broadband 24/7 communications with robots on Mars first and see how they do after that.

Also it's about time we did more robotic exploration of the Moon. Without the time delay - and if we had a capable rover, we'd surely do much better than the Russians did with Lunakhod.  The Apollo astronauts traveled as far in a couple of days as Lunakhod 2 did in four months.

With present day technology, semi autonomous rovers, collision avoidance etc, there isn't really any reason why we can't explore the Moon as rapidly as the Apollo astronauts did, many kilometers a day. The astronauts were limited because for safety reasons they had to keep close enough to their landing module to could get back on foot, before their oxygen ran out, if the rover malfunctioned.

Then,  without the limitation of oxygen supply, the rovers can just continue across the landscape day after day wherever we want them to go. We would learn a lot about the Moon that way. And also learn a lot about what you can do with robots and how best to do it.

And with humans on the Moon as well, we'd be able to do direct comparison, and learn a lot about how humans and robots compare as they explore extraterrestrial landscapes.

As for exploring Mars I think humans may well have a role to play because of our decision making capability. But depends how easy it is to get there.

If it's going to cost a hundred billion dollars to send humans to Mars orbit, well you could send a lot of rovers for that amount. And with broadband communications - they'd easily do ten times as much as they do now each day, possibly much more if you utilize the artificial real time gaming technology to overcome lightspeed delay effects.

It might be that we send humans for similar reasons that we send them to the ISS, with politics first, and science second. If so - humans could well have a worthwhile role to play even if it ends up being a more expensive way of exploring Mars than sending rovers.

Or perhaps travel into space gets much easier and we can fly into space as easily as we can to another continent and get to Mars in a week or two. There are ideas that could make either of these happen, or both. If so, it would then not cost so much at all to send humans to Mars orbit.

Then - the humans would be in orbit, and rovers on the surface, controlled via telepresence. This takes advantage of the best qualities of each.

I don't think we'd learn anything we couldn't learn using robots. But we might learn the same things much more quickly. But possibly at much greater expense. It could be worth doing even at 100 billion dollars if you feel it is important to learn as much as possible as quickly as possible. Because the rovers controlled from Earth would surely not be quite as fast as rovers controlled from Mars orbit. But on the other hand you'd have many more of them if you can spend that budget all on rovers and not on the humans. Which is best? 200 rovers on Mars all controlled from Earth, or maybe a dozen or so controlled by humans in orbit around Mars? I can imagine scenarios in which the 200 rovers are better, and others where the dozen rovers operated by humans is better. The 200 rovers would win if you want to study many areas of Mars with many different habitats. Do both of course if you have ethe budget, 200 rovers, many controlled from Earth but the human crew in orbit stteps in to take over the most difficult decision making from one to another, choosing whichever of them has potential for finding something interesting etc.

At any rate I think missions to Mars have to have the humans in orbit for now, until we find out more. Because humans on the surface greatly increase risk of introducing Earth microbes to the planet and the last thing we want is to find life we brought there ourselves. Robots can be sterilized, in many ways. So they are the ones we have to send to the special regions, and Mars is so interconnected, what with its dust storms and atmosphere, so, I don't think ou can really set up a situation where humans contaminate just a small region of Mars - especially when you take into account the possibility of a hard landing.