I have only skimmed this and the
Confession thread, but, no one has mentioned that many slots players believe that pulling the player card out "tricks" the system into allowing you to have another jackpot? In other words that the system "decides" that you have won enough or that you should not win, so playing anonymously or under someone else's name might allow more wins. That fallacy is commonplace.
As such, it could even be that some of these oddballs who allow a total stranger to insert her card in when they are playing, take one look at her and decide that she must not be winning much, so switching gears on the system might help them win.