It was a short-lived experiment. Motorola was sold to Lenovo, and the plant shut down, within a few years.
[0] https://www.theverge.com/2013/9/11/4717796/made-in-america-a...
That kind of assembly could be totally automated. Pick and place to make the boards, stack and rivet to put it together.
Modern phones have little pieces and wires all over the place.[1] You'd think these things would be designed for automated assembly, but they're not.
[1] https://www.iphoneincanada.ca/2020/11/15/part-2-ifixit-iphon...