Or more competition from older workers for entry-level service jobs, after the 2008 recession.

Maybe it's whatever is causing a more general decline in labor force participation?

https://twitter.com/AlecStapp/status/1481468372911116295

The 2008 recession apparently caused a precipitous ~7% drop in 25–54 year-old male labor participation rate, and it took about a decade to almost recover, then nosedived again during the pandemic. It has substantially recovered since the pandemic low, but we’ll have to wait to see whether it ever recovers to 2007 levels. It’s clear the initial government response to the great recession was too little, too slow, and insufficiently directed toward working people. Blame GOP senators and the Bush II White House.

Overall the US has seen a half-century of flatlining wages, massive growth in executive compensation, substantial decline of unions, financialization of many industries, business consolidation greatly reducing competition throughout the economy, outsourcing of many kinds of jobs, relaxation of labor laws, hollowing out and regulatory capture of federal agencies, an almost complete elimination of any limits on corporate/wealthy campaign funding, massive cost increases for housing and healthcare and education, etc.

Not really surprising that constantly empowering capital at the expense of labor for decades leads to long-term structural problems.

* * *

As an aside, it would be very helpful if these labor participation rates were broken down by age in smaller buckets. Such large buckets make it hard to disentangle demographic factors from changes for each age group.