As said previously. Lots of manufacturers do this. Some such as Apple even go further into the retail level and will demand where the phones and accessories are displayed in the store. If the store refuses to do what they say, then they are no longer able to sell Apple products.
In terms of who calls the shots it's Upper Deck. They supply the product. Once the product is approved by the NHLPA and NHL they produce the item. If they wanted to control the maximum price a product can be sold by distributors they could easily. At the store level is very different because there are thousands of stores but the number of distributors they deal with is a very small number.
They don't raise the price of e-pack. The thing is they don't stop products to get out of control in the original market so that when they have the product available on e-pack at half the price, people will go there to get it. It ends up hurting the hobby shops because if they have the product on the shelf for 150.00 because they had to pay an increased price from the distributor but it's available on e-pack for 89.99 those customers just flood to e-pack.
I blame Upper Deck more than distributors actually because they have the ability to control what prices hobby shops pay for their items. Heck they don't even really need distributors at this point it wouldn't be hard to ship direct to shops. Otherwise it would be easy to just say, you can not sell the product to hobby shops for more than x percent that you are paying for it. Instead they do nothing. At the end of the day it just hurts their brand though but from a business perspective it just turns off customers. Upper Deck as a company has been shady from the get go though.
Also if any of this giant price increases went on in big box retail Upper Deck would step in right away. The second a distributor would say your product costs 50% more to Wal-Mart then Wal-Mart would be on the phone with Upper Deck and the price would be back to normal. They have the ability to control the pricing till the item reaches the shop level. Especially in a monopoly environment where there aren't any competitors in licensed cards.