I studied in the United States (bachelor's and PhD). In my school, it was very common practice to list "TBA" (to be announced) for course professors, especially undergraduate courses. Through my years in the university, including becoming a part-time instructor myself as a PhD student, I got to know that it was pretty much always a logistic issue. Even if the department knew which teachers would be teaching the course, as long as they had not finalized the exact teaching assignment of who taught exactly which section of the course at exactly which times, such unfinalized assignments would be listed as "TBA".
In contrast, with graduate courses, there was usually only one section of a course each semester and so the known instructor could readily be listed as soon as it was confirmed.
In my school, students also complained about it. It is easy for students who would like to avoid a teacher with a bad reputation to suspect that the administration was trying to hide this information in order to make sure that the bad teacher got enough students in their class. But based on experience after several years in the same school, I don't think there is any reason to suspect ulterior motives; simple logistics led to this being a repeated practice whenever there are multiple sections of the same course.
(But since often when there are multiple sections taught by the same set of instructors each year, there will sometimes be a "bad teacher" among them; so, students would self-confirm their suspicions that the administration is deliberately trying to frustrate attempts to not choose a bad teacher.)
This is just a personal example, but I think the dynamics are very similar in many other universities.