Working in the electronic medical data industry, I can tell you that this isn't a huge surprise. We at my company encrypt 100% of all drives on all computers, and have a severe policy about storing PHI on any machine that isn't a controlled server (in a locked server room at a client location).
Unfortunately, there are lots of companies that are simply too lazy to encrypt hard drives before handing out new computers. With modern OSes its easy enough to do, but its a simple case of laziness on the contractor's behalf.
If there's any upside to this, the thieves are most likely just looking for cheap PCs to flip and have little to no incentive to go digging through files on the machines.