As a graduate teaching assistant at one state university in the USA, my answer is not necessarily reflective of all universities. Instructors mainly professors and also teaching assistants with the support of the course instructor have the leverage to create new courses and edit courses. The undergraduate program and the department stipulates certain knowledge that is supposed to be taught, it is the responsibility of the instructor to teach this information. However, how the information is taught is up to the instructor.
Instructors can create new courses. There is one instructor in the Biochemistry department of my institution who created a new elective course the "Biochemistry of Beer". He teaches students how to brew beer, teaching the students about the enzymes involved in the production of beer and the enzymes involved in the metabolism of beer. This is a lab course so the students get to actually make beer. The department is happy about this because the cost of running the lab is cheap compared to running a lot of other teaching labs, the department is also happy because the students are learning enzymology by brewing beer, and this fulfills one of the professor's teaching obligations and it is fun for him.
I am a graduate teaching assistant and my course instructor allows me revamp courses. I can teach really advanced modules in the course so long as I present the information simply. I have written computer programs to show the practical application of advanced statistics concepts that would otherwise not be taught in the biochemistry major. The biochemistry program is happy that I am teaching the students advanced applied statistics concepts that they couldn't figure out how to teach, the students are happy because my computer programs make understanding the statistics concepts easy to grasp, I am happy because my employment is more secure because now the program has evidence that I am a good instructor so they would rank me higher among grad students competing for Teaching Assistanceship positions.
Also, if you checkout for example the journal of biological education, the journal of chemical education, the journal of visualized experiments you will find creative experiments developed by instructors to teach undergrads. Most of the articles in these journals are original experiments that are cost effective and easy to implement in a lab setting.
Also at my undergrad university, there was a course called Biochemistry II. We are supposed to learn about stuff like amino acid biosynthesis, but the course instructor that year instead taught us strictly about the business of biochemistry. The course instructor got terrible reviews at the end of the semester, but he wasn't too sad because he started his own company. So instructors do need to teach students certain fundamental skills in their major.