That depends. Sometimes economics can make it impossible. Beyond that, if you read the article, it's not uncommon for truck drivers to only have one free day per week. How quickly can you learn a completely new skill set if you only have one day a week (a day, I might add, which is also your only rest day)?
Everyone is in a position to improve themselves. Take a class, get a degree, network, learn a skill.
It is not easy. But this is not the same thing as impossible.