I think the difference might be that to leverage the Netflix through T-Mobile you have to actively sign up for Netflix or switch to T-Mobile being the payment processor. Where as with the AT&T/HBOMax deal, you just login to HBOMax with your AT&T credential.

Interestingly, we're not on Magenta but one of the earlier plans so the OnUs benefit is for the HD teir of Netflix. As I said above, T-Mobile becomes the payment processor on the account so when I upgraded to 4K my T-Mobile bill went up a couple bucks to account for the difference.