Doesn't really matter if the luggage is lost or stolen. Either way, it's a security breach.
That's the part that upsets me so much. On one hand the security measures at airports are a major pita, for a 50 min flight from L.A. to Vegas you have to show up 2 hrs in advance, and spend most of it in line to have baggage opened and checked and checked again. Have to debate dive gear with mostly clueless people. Have to debate stupid incongruities between security measures and airline restrictions (i.e. tanks), and pay through your nose for it all. Then they hire riff-raffs to handle it all.
Unless it's cargo (a whole other subject that can get me going) there isn't supposed to be any unaccompanied luggage on airplanes. Hence, when your luggage goes on a plane you're not on there is a breach in security, and it's illegal. Plain and simple. Airlines should fined and baggage handlers charged, I believe that would eliminate a lot of lost luggage.
How, with all the supposed security, cameras, background checks some **** can just walk out of the airport with your rebreather is beyond me. But it's the same problem again: If you can get it out unseen, you can get it in unseen. We're talking about 40 or 50 lbs of metal, wires, hoses, batteries and electronics. All by people who load the planes, obviously unsupervised and unobserved. And some of whom are just as obviously having no problem deliberately breaching security and breaking laws for their purposes.