I don't think it's a big conspiracy like you think it is. Checking in is not the same thing as boarding the plane. The 2nd person seemed to have come in from another flight, presumably from the same airline. If that's the case, she probably checked in before her first flight for all of her flights that day - well before the listed checkin time. Therefore, she checked in before the checkin time, and your friend checked in after the checkin time - hence the discrepancy in policy.