Right? They must not think AI and automation can replace very many human laborers, otherwise they wouldn't consider declining birth rates to be such a crisis.
You can have both a labor shortage and mass unemployment. It occurs when workers are skilled for an industry with decreasing or no demand while another industry that requires different skills has increasing demand.
A good example of this is the high demand in the US for so called "Blue Collar" jobs. We have a shortage of trades people (Electricians, Plumbers, HVAC, etc) and far too many Business and Marketing people. There's 100,000 MBA's out there looking for a job and there's 100,000 Plumbing Contractors trying to hire someone.