Well, there is a reason for saying “almost”.
If we look at the present situation, then we could say that robot waiters still has a long way to go. Before they could start driving their human counterparts out of work, they have to fix some issues with their performance.
To start with, robot waiters are still incompetent in some areas. In the first place, they are still not capable of intelligent discussion. Although some robots can recognize certain voice commands, pressing a button is still the usual way to order. In addition, human waiters have the personality, plus the capacity, to entertain customers with their talk, as well as up-sell to customers.
There are also other technical details that still need to be worked on. For example, sudden changes in the path of the serving robots (running children, someone suddenly slowing down, spilled coffee or fallen plates, etc.) could hinder them in their work. Robots also have limited movements when they deliver food to the table.
Given these factors (not to mention the hefty price tag), human waiters can still breathe easily. They’ll just have to work better, or their boss might really look for a replacement.