Consideration, Chance, Prize are the three things you look for when applying the litmus test here. MUT along with trading cards in general do actually meet all three prongs to this test. The reality is they have been allowed to exist because it was never viewed as a big enough problem to care. This is something that may evolve with the digital age though.
Consideration means that there was a payment or exchange of goods to receive something back. Even if you are guaranteed to get at least something of equal or greater back it still meets the consideration standard. This idea that if you always get something back it's not gambling is false, contrary to popular belief.
Does skill matter in any way to dictate the outcome of the result? If not then it is considered chance, actually if it's not considered at least 51% skill it is considered chance.
Do you receive a prize for participation, or possibly receive a prize? This is an obvious yes in many cases but is still one of the requirements to establish gambling.
To see how this gets applied in the real world look to sweepstakes and other random drawing type promotions. When you see giveaways advertised you'll often times hear the term "no purchase necessary to enter". The reason this is stated expressly is because it removes one of the prongs to gambling thus making these giveaways not gambling due to the lack of consideration. Often times, if there were not a free opportunity to enter many of these sweepstakes (think McDonald's Monopoly) would actually be considered gambling.