Copyright laws does not restrict the buyer from reselling, that's called "first sale doctrine" or "exhaustion of rights". You can resell books and movies, you should be able to resell game licenses.
That depends, did the advertised product say "licence $game for £50" or did it say "buy"? If it said buy then I own the copy and can certainly resell it. If it said "license" or "buy a time-limited license" then as long as they made it clear "you can not pass this license to a third party" and required explicit consent to that, they're in the clear IMO.
Beyond that they're pulling a scam and those who hold ultimate responsibility for such scams should go to jail.
The concept of exhaustion of rights is probably ludicrous from a French perspective. The most common adjective used with the word rights in French must be "inaliénable", because most rights cannot expire nor be sold nor be taken away.
That's going to be a big culture shock for Valve. You'll forgive me for not going into more details but this would require a fairly long post to illustrate how different the law is.
That's first sale doctrine, it doesn't touch your author's rights.
Not arguing for either side here, just saying digital goods can be a bit more complicated than you're making them out to be.
First sale doctrine made sense when part of the cost of an item was the physical product itself, but with digital products, there's a near-zero production/distribution cost, so you're really only paying for the right to consume the media (book, movie, game, music, etc)
So in that case, what exactly are you reselling at that point?
The common digital platforms operate on a 24h or 48h rental basis. You actually don't own the movie. You pay to view it once, you could view it multiple times within that timeframe, then it's gone.
Yes. Reselling is actually equivalent to a refund from the authors' perspective. Problem is that people are too often reselling to buy their next thing rather than because they are dissatisfied with the product. On the other hand, refund policies based on arbitrary rules are not satisfying, too.
In the long run, the problem may be less books to read because less people will write them.
It is of course possible to look at this only from one side, but that approach - from either side - is not sustainable.
For example, every time a game is resold, the developer gets 10% of the resale value.
And I'm pretty sure that's why copying your own games/movies was decided legal here (as long as you don't share them), because the publisher themselves made it so the physical media is not the product.