Let me answer your question with another question. What prevents a bar exam for reading and writing? Would it be a good idea for such a thing to exist for the act of reading or writing books, news, or anything else involving language? Why should this be treated any differently for speaking to a computer?
He's talking about self driving cars, drones, hospitals, utility grids, etc.
Admittedly, it is hard to determine where or how you draw the line.