It's sad that people like that can't have a little dignity and make a living doing what they're capable of, but that's where we're headed.
1) Lack of knowledge of options. Let's say you wanted to get into the oil business. Without Googling anything, what job would you want? What skills and credentials would you need to acquire to get that job? How would you go about getting those?
2) Lack of education - Imagine trying to learn how to program without knowing what variables are. And then let's say you struggle and become capable of doing junior web dev work. What happens when you encounter even an easy interview question like "Write a program to find the first n prime numbers"
3) Lack of time - Most adults don't have time to focus full time on training, even if they aren't working. Children and elderly family members can suck up a lot of time.
The sad truth is that there will always be lower and lower-middle class jobs, because not everyone is capable of joining the upper-middle class. Should those people continue to experience a declining quality of life just because they haven't been genetically or socioeconomically blessed?