What is to stop a PPL hiring the club aircraft, paying for it, but then charging "the friend" for a cup of Nescafe brewed up in the club kitchen afterwards ? Not ethical, or approved by the CAA, but would that be "legal" ?
It really doesnt matter what we think. All that matters is what a court decides. This example is clearly illegal as charging someone for coffee or other unrelated products is irrelevant. I would hope a court would consider whether there is a clear agreement to SHARE the cost as opposed to make a contribution or do a deal. Nobody knows until the CAA decides to test it or is forced to test it. Caveat emptor