In most disciplines, the topics of the introductory sequence have not significantly changed since I went to college and even since my father went to school. In CS our introductory courses seem to change every few years. I don't think anyone currently teaches PL/C (or any other PL/1-variant) that I learned in CS 101 at Cornell. Computer Science didn't even exist as a field when my father when to college in the 50's.
In most disciplines any professor in the department deeply knows the material taught in the introductory sequence. Any professor could teach the intro sequence, or if they can't it's not because they don't know the material. This is certainly not true in computer science.
A professor at a state university noted that their CS majors had internships after their first year and commented "CS is the only discipline where we have to make the students employable after the first year."
In non-CS scientific disciplines, different universities generally teach the same material to their first-year students. Different physics departments teach with different books at different levels and maybe material in different orders but there is general agreement of what basic concepts of physics that first year students should know.
Go to any computer science conference and you'll hear discussion about what programming language gets taught at their schools. Nearly every department has people disagreeing about which programming language to teach to the first years. I tend to stay out of these fights for it is a lose-lose proposition. Win the argument and you'll end up teaching the class.