Do folks really expect to come out of college and immediately buy a starter home? No doubt some day, perhaps with parental aid.
Obviously, some factors beyond just salary are relevant. If I'm a single male, I probably prefer to live in an apartment for a while. If I have a nice salary, I may save up some and fix and credit problems and get a downpayment, and enjoy some time living in a nicer area than I did in school.
What the data show is that folks are buying at an older age than 20-30-40 years back.