I'm all for seeing items with random distribution inside as gambling too. I recall the monetary value of some pokemon cards caused my school to ban them. This didn't really have any effect other than to allow the school to say, "well, they are banned," if there was any fights or thefts relating to them. I think they probably had a net social negative amongst my friends at the time. In fact the only social positive I saw from them was in getting people, who wouldn't otherwise interact, interacting -- which wasn't always a good thing.
But I do see a few tiny differences in general between loot boxes and physical items like trading cards:
1. the packet does contain physical items which cost money to produce, whereas a duplication of a virtual item is effectively the distribution cost.
2. Retailers made a profit on physical items too. With virtual items sold by developer-publishers like EA and Valve, it's really just one party.
3. There is typically no limit on the number of loot boxes you can purchase. With physical items there is the stock of the shop.
4. Loot boxes can in some cases be purchased with other people's (usually parents) cards by default and without their immediate knowledge.
5. It isn't routine for somebody to give you a pack of physical tradable items for free to go and feel what they are like. If you go and buy them, there is a small amount of honesty in terms of what you are getting. With loot boxes, you are presented with them through in game events and then provided with the opportunity to buy more.
6. With physical items, you don't know how things are distributed but you can be reasonably certain that they can't be targeted at you. If you're looking for card X, the shopkeeper usually has no way of knowing what pack contains that and withholding that pack from you to maximise profit. You have no idea how the loot boxes are distributed. It is entirely possible for developers to detect when somebody is "hooked", work out what they are after, and attempt to maximise profit by withholding the desired item.
The only thing that could prevent such abuses is to regulate loot boxes as gambling as several countries have now done and respond with immense penalties where regulations are violated (a multiple of what would be made * estimated chance of being caught or a fraction of published turnover).