How the BLS defines the different levels of unemployment for the US

U-1, persons unemployed 15 weeks or longer, as a percent of the civilian labor force;

U-2, job losers and persons who completed temporary jobs, as a percent of the civilian labor force;

U-3, total unemployed, as a percent of the civilian labor force (this is the definition used for the official unemployment rate);

U-4, total unemployed plus discouraged workers, as a percent of the civilian labor force plus discouraged workers;

U-5, total unemployed, plus discouraged workers, plus all other marginally attached workers, as a percent of the civilian labor force plus all marginally attached workers; and

U-6, total unemployed, plus all marginally attached workers, plus total employed part time for economic reasons, as a percent of the civilian labor force plus all marginally attached workers.

Article never defines a living wage, and I don't think anyone really knows how to define it

"The recession made everything worse. Only 46.1% of white Americans over the age of 16 — and a mere 40.8% of Black Americans — now have a full-time job paying more than $20,000 per year."

Most children 16-18 should not have FULL-TIME jobs. Why are they even included in this statistic?