Banks make it easy to add authorized users because it increases likelihood of spending or overspending on the card, generating them more processing fee or interest revenue. It's definitely not out of the goodness of their hearts, nor out of any desire to give more than they get. It's not a Chase or UA thing; it's an industry-wide policy. Some businesses give full benefits on memberships for the primary + spouse (Costco), or discounted rates for a spouse or family member (some gyms). Businesses are in no way obligated to do that, though, and with the rampant abuse of the CC system (myself included) through churning cards and manufactured spend, there's no business/bottom-line benefit to granting full benefits to AUs, and it would definitely get heavily abused.

I really don't see how this is a benefit anyone could feel entitled to. Sure, I'd love my wife to have AC access from my AA Exec card without me, but I totally get why she doesn't.