"Why do employers demand a degree for jobs that don’t require them?" > This is a common practice. Speaking from tech industry experience, you'd be hard pressed to find a single job opening that didn't have a degree requirement listed. The kicker? It's not actually a requirement, it's there for formality.
" Technology increased the demand for educated workers, but that demand has been consistently outpaced by the number of people — urged on by everyone from teachers to presidents — prepared to meet it." > If this is referencing the tech industry, then this is an outright false claim. Tech industry job openings to skilled applications is something like 2:1, if not 3:1 right now. Since he just said technology in general, it might not be referencing the tech industry. Talking about the job market in general, I don't have any insight into that.
"The authors don’t speculate as to why this is the case, but it seems that students from poor backgrounds have less access to very high-income jobs in technology, finance and other fields. Class and race surely play a role." > Absolutely false. Race might play a small role depending on the state and environment, but class sure doesn't. No respectable tech employer cares about your financial upbringing, it's about what you have to bring to the table right then and there.
It really all comes down to how you play your cards. If you have the chance to attend college(which not everyone has the chance to do), you have to go with what will open the most doors. You can't expect to spend 2 years getting something like a liberal arts degree and expect to be making 6 figures. You have to research, you have to understand what skills are in demand. I will say that I am biased when writing this. As someone who grew up extremely poor and found opportunity through a tech degree in a local college, I very well have a world of opportunities now because of it. So it is infuriating that the author dares to consider the idea of even community college not being worth it, when it very well is one of the very few doors that leads to bigger and better things for low income people.