I once forgot my phone in a French airport (Lyon). Back then I had a "bulky" (hardened, like the crosscall brand) phone. I had trouble finding it in their system as they logged it as having a phone case.

I initially put up a request in their system, which did not match anything when they found it. I ended up finding it in their "public" listing (not really public, I think they ask for a ~10€ registration fee).

Anyway, when I got it back, I tried to argue with the employee that the phone did not, in fact, have a case. But they were adamant that it did. I ended up shrugging it off, happy enough to have my phone. But some people really don't care. Maybe someone filed your bag as something else, and then it wouldn't appear in the system, and weren't bothered enough to go look inside.