Why is this concept so hard for people to grasp?
Just because a copy is legitimate doesn't mean that it was legally obtained. No retailer is legally allowed to be selling the game, so any non-reviewer copies have been obtained illegally.
I get the concept. But it's not illegal for the buyer.
The shop has the contract with the publisher. They break it, their fault.
As a customer you don't have a contract with Bethesda like when you're allowed to buy a game. If it's in the shop, you can buy it.
No judge will convict you for buying a game earlier as it's not illegal. At least in Europe. Don't know about other countries/states.
That's why I wouldn't call it a illegal copy.
For the shop it's a different topic as they committed a breach of contract.