I bet the thieves didn't know, because this did not happen at (or close to) a quilt show or exhibition.
Years ago my car got broken in. I had only been away from it for less than 10 minutes. The thieves took everything that wasn't nailed down and then obviously checked later what they got. The police found all my belongings chucked over a hedge in a field about a mile away from where my car had been parked. The only items missing were several audio cassettes. If the thieves expected music, they were in for a surprise. They all contains German language teaching materials.
I very much keep my fingers crossed that these finished and unfinished quilts are found.
We can learn something from this, especially if you intend to move your quilts around quite a bit: Take pictures all the time during the process of making a quilt, so that you have some 'most recent' pictures of evrything for the police.