From Pew Research: The fading of the teen summer job
This can be interpreted as good news… teens are better spending their time self-actualizing, delaying immediate income in exchange for learning in-demand, high-paying skills such as coding, science, writing, math, physics, and economics rather than doing a dead-end part time job.
Due to a combination of a weak labor market and living with their parents, Millennials are delaying career and family formation, but in exchange are acquiring skills and a mindset that yields a greater pay-off in the long-run. Generations ago it was the opposite: people became self-sufficient early in life, but income and skills tended to taper-off after turning 30. Millennials, some of whom are approaching their 30′s, are far from achieving their peak earning power.
You also have to look at how the labor market is changing, especially in the past decade. Nowadays it’s harder to climb the corporate ladder, assuming there even is a ladder. We’re seeing the rise of the freelancer/temp economy. There a much bigger DIY element. In what can be described as a ‘hollowing out’ of the middle, the labor market is becoming bifurcated, with jobs being created in the low-paying service sector and the high-IQ creative class, but not enough in-between. This means that having work experience in low-paying jobs as a teen may not lead to better employment opportunities like it may have in the past.