Warner bros cited this law because winning their contest would likely violate this line.Funny... Every forum I've been a part of that had any kind of giveaway has quoted this law as reason for Canada being exempt, many of which have full legal departments advising them (Warner Bros. for one). There are other countries where extra tariff/taxes have to be paid by the contest sponsor, that's another reason.
Heck, there are even states in the US with laws making such contests difficult.
"Pursuant to section 74.06 of the Act, in contests designed to promote a product or business interest, adequate and fair disclosure must be made of certain information..."
I don't think the canadian skill testing question would qualify here either.
As far as things being illegal in the states, there are sweepstakes, lotteries, and contests. All 3 are similar yet different, and the differences are key in a situation like this.