I think the most relevant points contributed are the local cost of wages, taxes and property. In the UK and France, (where I live most of the time), there is a 20% tax included, whereas in New York, there is a small sales tax added afterwards, and then only if you live in the state. If it's shipped out, there isn't even that small amount.
Also, yes, the social services like free medical coverage enjoyed in Canada and Europe definitely costs a fair bit and the money has to come from somewhere. Property probably mixes in, but the lowest prices are places like Adorama, and I don't think you're going to buy their or B&H's buildings in New York City with leftover beer money.
I checked out Macodirect in Germany, and they are competitive. Also, there are good discounts available here in France if I buy 50 rolls at a time, which is no problem.
Isn't it all good fun?