"I'm not referring to the Halifax case specifically, but how the onus is on the Crown to prove consent in sexual assault cases when it isn't in other categories of crime."

I think you need to take a broader look at the consent issue. In most cases of criminal conduct (including sexual assault) the Crown doesn't have to prove anything about consent. The facts of most cases will clearly indicate that no consent was given and that, say, a robbery was committed. (A woman is knocked to the ground and her purse stolen. The police catch the thief a block away with the purse. There's no need to even raise the issue of consent and no defence lawyer in his right mind would try.) But in a relatively small number of instances the issue of consent can be a factor in determining guilt or innocence. And then of course it's going to be examined carefully because the consequences are huge.