Because launching a robot is a multi billion dollar affair and the robots we have launched are very far from the south pole. This is a whole planet after all, and they move on the scale of meters per second for maybe a few hours / day.
They don't have to be though. Spirit and Opportunity entire project budget (including design, building, launching, and operating for 90 days) was 820M. Even with the mission extensions the total cost is < 1B. And a lot of things have changed since then. Launches are cheaper, tech has improved and some recent missions have proven that even CotS hardware can exceed expectations (see the helicopter).
I would love to see NASA do something like the CLPS but for Mars. They could pay for launch services (which are way cheaper now with F9 / NG), and help with EDL (using the same parachute + airbags thing that has worked before), and leave the rover parts to 3rd parties.
We could have universities join the competition, building the rovers, exploring CotS stuff, autonomous driving and so on. Lower stakes than the decadal big rovers (Curiosity & Perseverance), but also cool and useful to train the next generations of students. Hell, I bet even companies could enter the race, with Toyota / Tesla / whoever else supporting this effort.
Are either of the rockets mentioned capable of launching a payload to Mars? The Tesla was launched on a Heavy which is 3 F9s. While maybe cheaper than a Shuttle launch, it's still at least 3x the F9 you're suggesting
Anyway, in a CLPS type program you could also cover kickstage development, like some of the new companies are proposing. Impulse Space is working in that area, developing intermediary stages that can take payloads from LEO to GEO, TLI and TMI.
[1] - https://www.spacex.com/assets/media/Capabilities&Services.pd...
It would be neat to see different companies, schools, or nations come up with variations on the rovers that only need to support the common interface of passing materials to the lab for analysis.
You could even drop more labs and build a network of them and expanding the range of your little rover nodes.
Once you have a decent rover design sorted out you can work on mass producing it and achieving economies of scale.
That’s still 2 or 3 orders of magnitude too high. The top speed of the Perseverance and Curiosity rovers is around 45 millimeters per second.