Dave Schneider's vintage Gibson guitar was worth close to $10,000. Thanks to Delta, it's now worth considerably less. Schneider, lead singer of the hockey-themed band The Zambonis, begged airline staffers to let him carry his 1965 Gibson ES-335 onto the plane, even offering to buy a separate seat for the guitar. Delta refused, forcing him to check it. When he reached his destination, he heard a "crazy sound [of] metal on metal," and you know this story is going to end poorly, right? That was the sound of his guitar being crushed in a service elevator, sustaining almost $2,000 in...