Besides the fact that they don't work yet (source: I'm working on it ;), a self-driving car can't bring the food to the door because the veteran is in a wheelchair. It can't knock on the door, have short chat, ask about the wife (who is deceased five years), and when necessary... Call elder care services when the veteran says he just talked to her yesterday.
None of this is part of the formal job description; it's the stuff that keeps real human beings from "falling through the holes" of the social safety net.
There's a lot of the web of government support of people that doesn't scale because the human-to-human contact is part of the point.