While it varies from program to program ... most programs assume that your original RN program covered the physiology and individual patient care topics sufficiently for you to become a competent, practicing RN. So they don't include much of that in the RN-BSN curricula. Remember, they are not trying to prepare their students to be competent bedside nurses -- you should already be prepared for that. They are also not trying to make you into an advanced practice nurse.
The BSN is an "entry-level" degree and they are just trying to give you the broader education to better prepare you some of the more advanced functions of some of the more sophisticated jobs at the staff nurse level and slightly above. Such roles include: preceptor, charge nurse, staff educator, unit manager, discharge planner, patient educator, program coordinator, community health nurse, policy writer, research team member, evidence-based practice project team member or leader, etc. Such roles are available to nurses without a Master's Degree, but not all ADN and diploma programs provide a lot of coursework focusing on the broader knowledge base that is helpful for such functions.
I teach online nursing courses in which half of my students are enrolled in an RN-BSN program (already practicing RNs) and the other half are pre-licensure students who already have Bachelor's Degrees in other fields enrolled in a "nursing as a second degree" program. Both groups need some of the same content (community health, health policy, leadership, research and evidence-based practice, patient education, etc.) -- so there is some overlap in the courses they need and they take those classes together. But their needs are not totally the same as the pre-licensure students need the clinical piece that the others got in their original RN program.