Some US schools are offering 6 year medical program as well, which are direct entry after highschool, which IMO is very good for those who are very serious about the profession. While obtaining a BSc is beneficial for life experience purposes, it does waste a lot of time for those who want to start working as soon as possible. Canada seriously lacks such program and instead insists on an undergrad degree (which btw, to get any real medical school to seriously look at you consists of 4 years of undergrad, not 3), or atlest a few essential undergrad courses to gain admission.
You are so right, UMDNJ (uni of medicine and dentistry new jersey) used to offer the 6 year program, had friends who went there. Not sure if they still do but I heard other places were doing the same.