You are mostly paying the tax man for those prices. The B&M also has a mark up.
Most 50g tins are worth $10 on average.
Is the Orlik Golden Sliced in Sweden that costs $50 seven times better than the $7 Orlik Golden Sliced in America?
No way, they are exactly the same thing...
As for bulk, it should always be cheaper than tins.
Tinning equipment costs a lot of money - either on labour for C&D's hand canning operation or in capital costs for machinery in the case of big automated companies such as STG...
This is what Gray was alluding to - an article on the subject by Russ Ouelette:
http://pipesmagazine.com/blog/put-that-in-your-pipe/packaging-a-tobacco-companys-dilemma/
As for Peter Stokkebye, if anyone has the resources to tin it is them. (STG) That line, however, is totally geared towards bulk and as you can see they are market leaders.
It is telling that PS Luxury Bullseye Flake is exactly the same thing as Orlik Bullseye Flake.
LBF is destined to be value oriented in the bulk-dominated American pipe tobacco market, whereas OBF is a tinned "premium" blend in the EU where there are no savings to be had by buying in bulk due to excessive taxation...
Roth makes a great point - buying in bulk can be good or bad depending on if you get the first of the batch, or the last of the batch. If you get a pile of less moist broken flakes, you can tell which one you are.
For that reason, I think that bulks are better for immediate smoking in many cases. They seem to get rougher handling than the tinned tobaccos.
Finally, as others mention, if you factor the price of mason jars into the equation then that is another hidden expense of the bulks that is already covered by the tinned blends.