Not mechanically the same at all. The reason they can skirt by and have not been considered 'gambling' is largely due to the fact that you always win something, even if the player to player market dictates that item as worthless.

A slot machine literally just takes your money and you are left with nothing but having pushed a button for the pretty lights and fun noises.

It may be problematic but I see it as less problematic than non-cosmetic items like Magic card packs