So AT&T doe snot offer seniors discounts. They offer AARP members discounts. Should be an easy win for T-Mobile. But with the law, nothing is ever easy
It sounds to me like their claim is (or should be) that T-Mobile should've had a 4th box, "become an AARP" member, as an alternative. As it stands, T-Mobile seems to be misleading people by suggesting they don't have that option. Though I guess I can see why neither of them would actually want to say this out loud.
Are you sure? That page says it's ages 50 and over, which seems like a senior discount. Reading here [1] I see So can you join AARP if you’re Under 50? Yes [...] However, you won’t necessarily get all the benefits available for those over 50. For example, some discounts offered by retailers have age restrictions and require you to be above 50 to take advantage."
One need not be a senior to join AARP [1], though some benefits require it. It's not that different from other membership schemes in practice, which is a fairly common business model for special interest groups.