This is a great song about United Airlines. In reality, they are all the same. I flew American Airlines and made the mistake of checking a bag. Upon arrival, it was clear that the zipper was cut for I had a lock on it. They said they were not responsible for zippers and it just got caught on the conveyor belt and somehow that was my fault. Six other people had the same complaint. They told us all get lost.
If you do absolutely have to check a bag and they charge you for it anyway, send it ahead. There are new services popping up because the airlines charge too much, take no responsibility, and no longer treat you as a valued client but more of just a sucker to exploit.