Don't know how it works on the backend, but lounges get compensated for each person entering that isn't affiliated with this home carrier. So whether this is because you are a UA club member or *G, I don't think it makes a difference (though perhaps specific rates paid are different/negotiated separately.

My guess is because * has systems that are interconnected that can verify *G status, but probably not lounge memebrship (which is mostly unique to North American carriers, anyway), there is probably a separate and more involved verification.