The 16-18 year old segment of that group is high school kids. In my area, it appears that there are a lot fewer jobs avaialable than when I was that age. For example, my friends and I were all "paper boys" delivering various newspapers. Now I notice middle aged people flinging the papers out of cars. We also used to mow lawns and shovel snow. Those jobs are all taken by professional landscapers. Also, many parents would rather their high school kids did school-related activities than some low wage job.