our labor force participation rate hasn't recovered since the recession. 65.7% participation rate in september of 2009 compared to 63.2% today. look at the official data yourself:
https://data.bls.gov/cgi-bin/surveymost?lnthe "low" unemployment is a result of nearly-unemployed people working small jobs which aren't enough to cover their basic needs rather than a genuinely improving economic situation. remember: 5% unemployment is normal and ideal because it representes structural unemployment plus the churn of people moving from job to job. we're lower than that now, which means that either our metric is not reflecting the scenario (as i believe) or that the fundamental amount of churn and structural unemployment has decreased, which i think nobody will try to argue.
the people knocked out of the labor force in 2009 have had an extremely difficult time getting back in, and the jobs they occupied have been destroyed permanently by the looks of it. in other words, while unemployment is very low, compared to then, the economy either has 2-3% fewer open jobs compared to the number of jobseekers (who may be employed), or employers are substantially more reluctant to take on new employees when those employees are not already participants in the labor force. or both.
there's two additional problems here. the first is that employers are unwilling to give unemployed and marginally employed workers a shot because they're tainted. this is especially true in "professional" and "high quality" jobs. the second additional problem is that middle-class people tend to hold out for a "good job" rather than taking any job which they could reasonably do, like waiting tables etc. knowing this, employers often refuse to take these people for those roles...