kimzyhoe: In addition to what Chwirky said, courses such as biomed aren't all exactly the same, so medical universities would not have graduates that necessarily have the same knowledge as each other, or the same knowledge covered in the first 3 years of medical school.

As it is, another reason is the first 3 years of medical school can also vary quite a bit from one medical school to another, so no biomed course could cover all the stuff if it tried.

Bearing in mind, biomedical sciences isn't just meant as a jumping board for medical applicants, but often as a stand alone degree qualifying someone to work in a lab (sometimes requiring extra training) as a biomedical scientist. As such, the aim of biomedical science isn't to specifically cover half of medicine, but to teach medically related sciences, often focusing in more detail on the core scientific background or lab analysis around a subject.

And to clarify what dances_with_lamposts said: graduate entry medics on the 4 year course have a shorter course because the first two years of medicine are condensed into one. They do not 'skip' anything. They may not even be science graduates, so it cannot be assumed that they already know all the basics. They have a shorter degree because they have longer terms and probably more lectures. You probably need to be a graduate to be able to cope with the pressure of something like that!