the developer needs to write code to detect the current profile. Most app’s don’t do this, and they explicitly ask a 2nd time. Not apple’s fault.
There are some apps that get this right. Infuse recently added support for this.
I don’t know I think Apple should be able to keep COW filesystems for every user to apply atop a read only file system. Unique apps, unique settings (maybe unify tv settings into admin panel) and no cross-contamination or need for app owners to switch profiles. macOS software doesn’t need explicit understanding of profile switching, neither should iPadOS software.
It's not the end user's problem whose fault it is.