I think approachability is absolutely key. Kids wrote programs on their Commodores, Ataris, and TI calculators because the environment was already setup. You could type in a few commands and instantly have something running (a program that solves the area of a triangle or one that plays a cool sequence of tones). There's only one editor and one language.

The majority of today's 10 year olds are not writing twitter scripts. It requires a significant amount of understanding and time to do so. You need to pick a programming language, install it, figure out how to write your program and how to execute it. The barrier is a lot higher than writing a program for your calculator during math class.

It'd be much easier for you to find people who wrote trivial programs on their Commodore when they were 10 than it would be to find 10 year olds who are writing python.