Most people still work manual labor jobs. Cognitive ability also declines with age. Age discrimination during hiring/recruiting is fairly common (witnessed it at nearly every job I’ve ever had, even though it’s illegal, and I’ve had a lot of jobs). There aren’t enough “bullshit jobs” like Walmart greeter for everybody. Aging population can be solved by permissible immigration (which are comparably younger populations), but there are too many racists and politicians worried about demographic shifts.