Earlier quoted context omitted.
Apple often tries to re-engineer the thing they develop.from the ground up. Seems it started this way on Titan, too, then scaled back and decided to focus on the main problem: safely getting around. Nothing wrong with this I think. On reinvented wheels, early ideas rejected today may get a second life later, e.g. spherical wheels for moving in very constrained environments.
I can't see spherical wheels working well. They would have a smaller contact patch on the road surface than a standard wheel, and consequently less traction.
But those ideas are tangential (being generous) to self-driving, so better not steal cycles from it.