There are many reasons for the human touch to hope. In one case, Duplex does not appear to take the clues that the reservations are available. Training may also require more real calls to the world before each situation is handled. Above all, the company is debating that it conducts a careful strategy. Treatment for entrepreneurs wants with respect, and this means gradual transition to AI as it becomes better-suited to dealing with staff.
If there is a major concern, this may be that Google has oversold Duplex capabilities. It builds technology capable of managing all types of reservations, but is not always true. There are still lots of studies left to do, and it may take a while before you can imagine an AI will do such activities.