I know a few people that work and worked at McDonalds long term. It's a stable job with a flexible schedule. Granted they aren't trying to raise a family on that paycheck, but I'm sure there's people out there--especially in the current job market--that are having to.
What gets me is the assumption of a second job. That's not always an option, for various reasons. And not all employers will deal with you having a second job.