They're also used for low-volume prototyping or short-run manufacturing, not just high-volume manufacturing. They're especially useful for placing high-density components; it's not exactly easy to assemble a PCB with BGAs by hand.
There's one for $1799 intended for prototypes.[1] It's clever; it uses more vision processing and less tooling than other pick and place machines. Parts only have to be close to the right place; the vision systems do the fine adjustments.
Unfortunately, few people seem to have one working. There are two hacker spaces that got one, and there's even an unboxing video, but didn't get it assembled and working.
I could use one of those occasionally. The tweezers and microscope thing gets tiring, fast.
I have this cheap one.[1] It doesn't work. The "squeeze the rubber bladder to get vacuum" approach doesn't provide enough suction. Ones with a powered air pump might work, but cost much more.
Theirs is a reel-fed machine. Those are how most of the world's electronics is made, but making a single board without reels of the same part is tough.