What does a kid need a special debit card for? When they’re old enough to get a job they can just get a regular bank account.
We advertise sugary, fatty, fast food to them on the TV shows they watch. We get them addicted early to the dopamine hit of a the next big toy, an obsession which carries through to high tech gadgets and cars in adulthood. My local grocery store even has a tiny child-sized shopping cart with a flag on it that says "Future Customer in Training", so kids can mimic their parents as they consume.
In that context, debit cards for kids are a logical next-step. As soon as they hit 18 and can earn an income, now companies will have a nice fat history of buying habits and consumer behavior for these kids that makes them easily targetable.