UAC isn't some massive information centre with total dominion over the application process - UAC is an intermediary that makes the application and offers process as fast and efficient as possible.
UAC holds your credentials - your marks, your UAI, and your preferences. These data are passed to the universities you have applied to, who consider you for all courses you apply for. Once all applications have been considered by the faculty, the university decides who it will make an offer to (ie who qualifies) and sends this information to UAC for all courses. UAC then compares the courses for which an applicant qualifies with their preference list and finds the highest offer on the list. All courses below are no longer considered, as they are lower preferences - UAC notifies the universities that the application for that course is withdrawn (due to higher course offer) and the process is repeated until all places are filled.
Considering the intricacy of the system, it is comic that you would want everything to happen overnight.