my experience across several *A carriers is: it varies. my most recent experience was with Thai Smile. they provided the benefit only for the *A member, not the others on the same PNR. And since I think that most UA FFers that are using *A carriers are doing so outside of the US: Also note: outside of North America, most airlines use the weight rule, not the piece rule. That means that you are allocated a total amount of weight and it can be distributed across several checked pieces. There is a maximum allowable weight for a single piece. but the North American 'piece' rule limits you to a fixed number of checked items (1 or 2) regardless if that has consumed the theoretical total aggregate weight possible. And finally, not to over explain but: If you are on a multiple leg flight, with a connection(s), then it will be the rule of the first carrier that will dictate the rules for that segment. Thus, flying UA/ANA from USA to KUL you might get 2*70# for the outbound, but only 2*50# for this return. Both directions would be on 'piece' basis because NA is part of the trip.

And some theoretically *A carriers in Europe (looking at you, Lufthansa) have some discount tickets that do not allow any baggage with out a fee. Even for a *A member.

Short version: unless you have something in writing (like an eTicket) that confirms extra allowance to all flyers, then you should not count on it.