I think that is part of the equation. Another part may be the limitations on what kids can do, which renders them less useful to an employer.
My first job after doing a lot of farm work on my grandfather's and great uncle's farms was driving sheeting on a seawall crew with a 110 lb sheeting hammer. I was 14. It was hot hard work, but paid much better than minimum wage (got me in shape, too).
Nowadays, kids just are not allowed to do that sort of work.
I just can't blame them for not being excited over a fast-food job.
I'd love to find a kid that would help out around my farm. Over the past 10 years or so I've hired, on average, one to three kids per summer to help out with mowing, weed eating, fence repair, etc. One kid out of about 15 I've hired actually stayed with me all summer (and he made a pile of cash in the process). The rest lasted two to four days before they either quit because "it's hot" or I had to let them go because they just wouldn't work. After the first two days of work, I reviewed the efforts of the most recent kid I hired this year and he blew up at me, screamed a bunch of vulgarities, flipped me off and told me to go do something that is physically impossible. This was a 13 year old, no less.
I pay cash, daily, and it's much better than minimum wage, but I expect them to work and work hard for their pay. That doesn't seem to fly with these cry baby kids these days......