Hopefully this wil provide a little clarity as to why some brands of optics demonstrate a greater price gap between Canada and the US.
For brands where dealers can purchase direct, the gap is relatively insignificant. For example, a brand new Swarovski Z3 3-9x36 plex/4A rifle scope is $779 US minimum advertised price (MAP) and anywhere from $799 to $819 in Canada (with $799 being considered Canadian MAP). Dealers can purchase directly from Swarovski Optik North America (US division of Swarovski Optik) and dealers pay a bit more than their US counterparts due to fluctuating currency, higher freight charges, and importation/customs charges. However, as stated, the price disparity is reasonable.
For brands where dealers must purchase through a Canadian distributor, the gap can be significant. Zeiss products are distributed by Gentec Canada, hence anyone wanting to sell Zeiss must deal with Gentec and not Zeiss, as Gentec has the distributorship for Canada. While Zeiss sells to Gentec (based on volume) at a better price than it would to a street level dealer, Gentec takes a mark-up (probably around 15 to 25%), which results in Canadian dealers getting a product at a significantly higher price that their US counterparts: Conquest 10x42 HD binos have a suggested Canadian list of $1,129.99 with a MAP of $1,059.99, while the US MAP is $999.99. On some items, the disparity between the price US dealers are paying and the price Canadian dealers are paying becomes clear (and hard to take) when a US dealer puts an item on clearance or "demos" the unit.
As for MAP being "price fixing", that is not a dealer choice, it is mandated by the manufacturer. The penalties for violating MAP as a dealer are quite clear in the dealer agreements, and dealers have lost lines as a result. One should also note that with many brands (Premier, Meopta, Minox) there is virtually no discrepancy between Canadian and US pricing. Conversely, for some brands (such as Schmidt) Canadian pricing is actually less than US pricing.
However my policy as a dealer is that, whenever possible, I observe US MAP pricing - given that many US retailers can sell into Canada it is competitively disadvantageous to force Canadian retailers to sell at a minimum price above US pricing (with a par dollar). If a line clearly indicates that I must observe MAP in advertising, however I can sell below MAP if it is not advertised, well I'm always willing to talk turkey!
Hopefully that provides some clarity.