...does "overqualified" mean "has a degree but can't be trusted to change a lightbulb"?
Because ya. Holy hell, ya.
Not exactly. I have an MA in International Relations, a BA in History (yes, I know, non-stem, I'm a clueless humanities major, etc, etc). However in high school I was in a science and tech Magnet school and took AP Bio, Genetics, and honors math courses. Almost went to Ga Tech to get a degree in biomedical engineering, but decided to do something different.
In any case, my first full-time job out of grad school was working cargo for a commercial airline for less than $13 an hour. The only reason I even got that job was I had been working for that company part time all throughout college and had built up seniority among part-timers. I was about ready to join the military because I couldn't find any other work but developed a chronic back injury that prevented me from doing so. Did that for about 1.5 years until the beginning of this year when I got a new position with the same company, for which I in part credit my graduate degree. So yes, it is perfectly possible for intelligent, skilled people to end up in a job well below what they are qualified and able to do.