so I spoke with a friend at another airline who is fairly "high up".
PP payments aren't a simple "$20 per visit". There's an algorithm based on # of usage per month, per airport and it changes. He said its not like partner airlines, where you WANT partners inside your lounge - because those can become a liability if they don't allow them in.
Example: American/Alaska. If 25,000 AS members entire the Admirals Clubs each month, AS would need 25,000 AA members to enter the AS clubs each month. That way there's no billing or money back and forth, UNLESS its tied to another benefit. Star Alliance lounges, however, are handled by reimbursements based on the # of entries per month from each airline - for example. Star lounges are not meant for "profit" - which is why most alliance lounges may tend to be a bit nicer than airline-sponsored or backed lounges.
Airline paid memberships are meant to "pay" for the club in their annual budgets. Day passes and programs like Priority Pass are just extra money on top of it. Rarely will an airline actually go into financial deficits for lounges, just for lounges sake.