The article itself pointed out that their headline number doesn't really account for pre-college differences between the two groups. For example, someone who

The article itself pointed out that their headline number doesn't really account for pre-college differences between the two groups. For example, someone who grows up in a stable high-income environment will likely go to college, but that is because they have the support structures that will assist them prevent them from falling too far behind and help them recover from any setbacks. A person who might want to go to college but is from a disrupted lower-income environment may not have the support structures that help them get through college and find a good job. From the article: This calculation is necessarily imprecise, because it can’t control for any pre-existing differences between college graduates and nongraduates — differences that would exist regardless of schooling. Completing college may simply be correlated with having a well-paying job because the skills required for both are very similar. A second study, linked from the article, compared people with similar jobs and those with and without degrees, e.g. secretaries. They still found a gap, but again they did not control for for pre-college environment.