You can present it wrapped in whatever glitz (or lack of) that you want, but the process is pretty much the same.
You're exchanging currency for a chance at getting something from a known subset of items.
You could write a terminal program in which people can buy and open loot boxes; I guarantee you it won’t be as “effective” as a fancy loot box ceremony in an AAA video game.
(I put effective in quotes because it depends on what axes you’re looking at.)
Pokémon cards are clearly different enough is enough ways that they don’t cause the same amount of harm to anywhere near as many people as other forms of gambling do (such a pokies machines in bars and loot boxes in video games).
Sure, the core process may be the same, but that’s not all that matters. It’s how it connects to everything else and what the overall resulting effect is.
It's very different than having a number invisibly go down from your playstation gift card or a number invisibly go up on their parent's credit card.
Regarding currency, the real-world monetary cost is kept discreetly out of sight of the player, much like tokens are used in casinos, as part of the sleight of hand. They're not exchanging cold, hard cash; no, no, that would be crass. They're merely exchanging "gems", "crystals", "orbs", etc.
If you have to hand over some number of physical tokens, and actively see your stash of them diminish, it's going to hit differently than letting someone handle your card, and then a number that you have to log into the bank to even see goes down.
I see ads for programs where you give your kids their allowance on a prepaid debit card, so it could get to the point where you could reach maturity without ever touching a dime. Will those kids be as frugal as the ones who got notes?
When you buy a loot box, you get some bits set on your account with the loot-box-seller. You can only resell them if the publisher lets you, and only via publisher-approved methods.
The reason this is a meaningful point of difference is that you no longer have the "I want X, and the only way to get it is to keep buying loot-boxes and hope". If you want a specific M:TG card, someone is happy to sell it to you for the right price; you don't have to dig through booster packs.