Paper routes were pretty exploitative. The children, often around 12 years old, were/are treated as independent contractors who buy the papers and have to collect the money themselves. Deadbeats could avoid paying for some time, usually until a parent chewed them out. When you went on vacation you were responsible for finding your replacement and paying them.
Throw stranger danger into the mix and it's obvious why kids aren't doing paper routes anymore.
I'm pretty sure that's also because the number of households that get newspaper delivery now is so low, and so the density so low, that it's necessary to have a car to do it.