Venus also does not have plate tectonics, but Mercury does as announced on this Monday! There are certainly theories why this is for Mars (too small, would require water), but I guess most of these just went into the recycle bin It might be linked to the magnetic field question: It has been argued that the core of Venus lacks convection, because no subducting plates bring cool material into the interior of Venus. But it might also be the other way around: because Venus has more or less thermalized, there is neither plate tectonics nor a magnetic field. I have read more about an inductive response to the Jupiter's magnetic field. But there are also scientists arguing for a dynamo, so I do not think this has been settled, yet. It is in orbital resonance with the other major moons, though. I would expect the moons exert little force on each other by now, Certainly reasonable, but since it is two out of four, you can make up plenty of reasonable theories that fit the data, so I am not convinced of any explanation.