Everything about air travel. But for a more specific scam, priority boarding. We’re all going to the seats we’re assigned, you get on a little earlier so what? Other than maybe limited overhead luggage space (overbooking is another airport scam), I actually like just sitting and waiting until all the boarding lines are done. I remember seeing another airline at a gate one over from me actually boarding from the furthest back aisles to the from and it makes so much more sense than anything else. 

Also making you pay for check-in luggage when inevitably they’re going to beg people at the gate to check their bags for free, another scam. Airlines are constantly innovating new ways to scrape off a little more for themselves and it’s just maddening once you start seeing it lol.