There are other reasons for people to not be passionate about their job. That said, having a boss who doesn't respect you can seriously sap your motivation.
Not only was I not passionate about that, but since it was the first time I'd encountered code with lower quality and even more antiquated technology than what I'd found in government contracting, I was truly contemptuous about what I was doing.
If you get stuck with work that doesn't require ANY of the skills that the interviewers grill you for, it's hard to care about your job, let alone be passionate about it.