Earlier quoted context omitted.
Why do you need the first 4 years undergrad - in places like the UK you can go straight to study medicine from secondary school at age ~18?
The belief is -- and it is one that I share -- that this makes for more well rounded, human physicians. Additionally, a greater depth of thinking leads to better diagnosticians, and physician-scientists as well (IMO). Now, all of this is predicated on the traditional model of the University education, not the glorified jobs training program that it has slowly become.
Course acceptance is initially driven by academic performance, and ranked scoring.
To get into Medicine at Monash and Melbourne Universities, you'd need a TER (Tertiary Entrance Ranking) of 99.8 (i.e. top 0.2% of students). This number was derived by course demand and capacity.
But, during my time, Monash was known for having a supplementary interview process with panel and individual interviews - the interview group was composed of faculty, practicing physicians not affiliated with the university, psychologists, and lay community members - specifically with the goal of looking for those well-rounded individuals.
It should also be noted that though "undergrad", there's little difference in the roadmap. Indeed when I was applying, the MBBS degree (Bachelor of Medicine and Surgery) was a six-year undergrad (soon revised to five), with similar post grad residency and other requirements for licensure and unrestricted practice.