"As we continue to collect data over time, the system will become more robust."
This is one of these statements that sound true and I know Karpathy coined the term "operational vacation" but it's not clear more data always equals more robust system.
Of course, however I imagine that the self-driving feature space is so large and so hard to collect that they probably do have lots of room for improvement simply with more data.
It is for the "learning organization". If Musk is able to continue a generative culture within Tesla more data will equal a more robust system. If Tesla changes to a "rule/process" or "power" based culture, your concern will come true.