Usually despite being banned by the TOS, as a black market kind of operation.
More problematicly, im not sure how youd stop it from extending to say WoW gold-selling, or even cartridges with 100% saves on them.
People will attribute value to anything for any number of reasons, but I’m not sure you can make regulation on anything beyond “encouraging” such behavior. (And I would assume these companies already actively discourage it; you’re not supposed to be able to get money back out of the system!)
This doesn't actually get money out of the system. If I sell you my WoW account, money has changed hands but none of that money has come from WoW/Blizzard.
There are some game developers looking at sanctioned RMT right now because it would be a huge selling point. "Make money playing video games" used to be a popular slogan on tacky banner ads. That could see a comeback in a different way.
Sanctioned RMT works through some official marketplace (think Diablo 3's ill-fated Auction House). Not only does the developer not pay out anything (all money flowing through the auction house is coming from buyers of items), but they even take a "transaction fee" cut. All while continuing to own all the items being traded. There's no downside for the "house".
Except perhaps suddenly running afoul of gambling regulations if they can no longer argue there's no "prize" element to the gambling?
We're well past the point where virtual entitites are imaginable by the general populace.
Getting a virtual gun, creates an actual advantage in the game your are playing online.
While ultimate ownership of the code may be fraught, but practical day to day ownership and usage is not (unless you are fighting a particularly contrived case).
So, if a player does not have a title to anything in the game, the player has control over some items, and can sell this control? I suppose tokens in casinos also don't belong to players, but they are readily exchangeable for money.
On one hand, this may be enough to consider it gambling for money.
On the other hand, many games may expressly forbid selling in-game stuff. This is not easy to enforce, though, unless you forbid to drop and pick up items, or make in-game exchanges. A number of games uses exchange as a important "social" / "multiplayer" feature, but likely those are not slot-machine-like anyway.
It is extremely easy to enforce: just make items non-transferable, so they can only be gained by actual questing. As soon as an item is gained, it is permanently associated to a given account.
Tie them to a really name and government issued photo id? Please note I hope that this does not happen but that is one logical (very scary) conclusion that regulators may reach when that question is asked.
Yet loads of people sell their in-game items (that they got through chance) for real money. So in a sense, they do own them.