Exactly. We also have to consider how advantageous Earth's moon has been to our existence. When photosynthetic life evolved, the Moon was much closer than it is today and had a considerable effect on oceanic tides compared to the present day. The Earth's rotation was also faster, the planet was cooler, and the overall landmass was smaller and closer together. The result was few shallow seas but strongly affected by lunar-driven tides, providing just enough safe habitat for these oxygen-producing organisms to outlast what was arguably life's greatest mass extinction on this planet to date.

Without a moon like Earth's, or plate tectonics to alter martian landmass, Mars's biosphere lay at the whim of volcanism, hydrogeologic forces and impacts. If there was an oxidation event like ours there was no variability in global ocean levels for any organisms occupying the land-ocean border region to find "short-term" refuge execpt by glacial forces or rainfall. On a geologic timescale, any relatively large event in the midst of a rapid change to atmospheric chemistry by photosynthetic oxygenation would have been game over for life on Mars. Any chemosynthetic organisms such as those on Earth which thrive deep underground, by hydrothermal vents and other thermophiles could have a chance of survival until the ocean vanished and sealed life's fate on the planet. It remains to be seen whether we can find anything near the surface or deeper underground where life may still cling.