Think about population (tax base) size vs. services provided vs. land mass.
Different tax systems, internally as well as externally (tariffs/duties).
Can you imaging having Canada's population in a country one third the size of BC? Welcome to Poland. Probably cheaper schnitzel there, given amortisation of trucking rates, etc. Running, and maintaining, a cell network in Poland is probably going to be cheaper than stringing a single line of towers to Prince George, never mind Fort Nelson.
On your last comment, personal/business experience tells me that yes, Blue Line pays a different rate than their US counterpart. Again, tax systems, and throw in economies of scale. Never mind border shenanigans, and the associated cost of wait times and storage/brokerage fees. On this particular firearm, throw in the time and money spent researching and submitting for the FRT. Also trying to make up for trying and being denied for previous FRT designations, or hoping to put some money aside for future submissions.
Personal example: I purchased a scroll compressor for my heat pump out of the US for less than my buddy, a distributor for the brand, could wholesale it to me in Canada.
I find it odd that people up here either A: See this as a grand conspiracy between retailers, or B: Think pricing should be the same in completely different countries. If either was true, why wouldn't a Canadian firearms retailer drop their prices to the lowest on the planet, and blow the competition away?