Hi ftrichard, it's good that you are very aware of the scheme and how it works - I believe you do travel alot to know this or have research alot.
As a layman passenger who was faced with limited choices of food in the airport during an early morning flight, and with Mastercard signs posted throughout the airside leading to the lounge, I had thought it was worth a query at the lounge as to how it worked since I had a Mastercard.
I wasn't expecting the visit to be free, but would have appreciated that if the staff wasn't sure of how the system work, he would have advised me that he wasn't sure if I would be charged, rather than telling me it was free (I asked twice if it was really free as well). And it certainly didn't help further with the negative experiences I had when contacting Loungekey.