The reason Canadian corps like Rogers, Bell, etc. are so strong is because our rules...
I'm the Canadian that helps manage the Audioholics contests from Canada and I can confirm it sucks. But it would add complications. Ultimately its up to the vendor that sponsors the giveaway. Most companies can't easily ship for free to Canada, even bigger companies that have a presence in Canada, such as Masimo that sponsor an Audioholics contest do so from their USA branch that their Canadian arm has nothing to do with.
Canadian businesses are cheapskates anyway. A "deal" in most Canadian retail is getting .10-cents off something and it's promoted as a "bargain price". I go to the LCBO to buy a bottle of whisky and its considered "On Sale" if they reduce the inflated price by $1-CND. Good luck getting a promotional "giveaway" from any Canadian business, it's very rare.
arberda2 is right, even if it doesn't directly affect Audioholics giveaways. Canada's CRTC is the equivalent of the US FCC. If you read the About Us page of both agencies, the FCC has a pretty straightforward mandate. The CRTC OTOH, is downright Orwellian with talk of managing "Canadian Culture". The implications are a bit scary for a government agency dictating "culture". The CRTC is effectively run by Rogers and Bell executives and it's the reason Canadians pay more than any other country for wireless data and other services. They maintain protectionist policies to prevent competition as they collude on pricing.