Because of their ability to provide high thrust and accurate positioning, ballscrews can be found in many automated assembly applications that require linear motion.
Parts fixtures don't actually do anything, like weld a joint, yet they're the first part of an automated assembly system that gets made. They represent a small part of the overall system cost, but if they fail, even the best-designed machine will produce junk. In truth, "start with the part," the axiom of automated assembly, could easily be "start with the fixtures.