The topic wasnt answered because it was stated as "Would you like to know why the North American tree is so inferior compared to the Brazilian one?"

The way this sentence is constructed made it look like the person knows why.

Why the rewards are different is because of the different player bases. We also have most of those ninjas in our Tree in the form of our current existing optional packs. The only ones not in the current packs are Pain and Madara [FB]