This is a wide spread issue. Customs does do it's share of theft, butchering or whatever else leads to the item never reaching it's destination.
I lost two items coming through customs in Trenton, NJ. A kozuka from Germany, and a ubu Kikuchi Yari from Japan. With the Yari, I was finally able to speak to someone at the facility and they opened an investigation. In a mere Two days they sent me an email stating that after an extensive investigation (2 freaking days) they determined the item had never been there. Yet Japan tracking clearly documented it's arrival to NJ. The kozuka was insured, the guy who sent the yari did not insure it, total loss.
USPS is just as bad. I shipped a sword to MS and it was routed through the huge hub in Memphis where it disappeared. The buyer lives nearby and went to the facility where he showed an employee a photo of the sword. She admitted to seeing the sword. She said it had come out of the box and therefore was sent to Atlanta to the "dead mail center". Buyers father is a prominent attorney in Memphis who contacted his friend the senator. Once they became involved, the sword miraculously turned up in Memphis, not Atlanta. The lying bitch at the PO is probably the one who stole it, she damn sure didn't send it to Atlanta. Box was crushed, sword completely undamaged.
I have friends who have lost things, high end things coming through customs and San Francisco as well.