Manipulation will scale faster than driving because a robot can make a mistake, fix it and learn from it, and a car cannot.

And when you make a mistake and correct it, well, first you you've achieved the task because you've corrected, but you've also gained knowledge that allows you to avoid that mistake in the future. With driving, because of the dynamics of how it's set up, it's very hard to make a mistake, correct it, and then learn from it because the mistakes themselves have significant ramifications.