If these are indeed the cellular ones, you can be certain that the second they are turned on they can track exactly where they are. In fact even if they aren't, the second they connect to Wi-Fi they will know where they are.
No doubt that Apple has a manifest of every single iPad lost and the serial numbers, MAC addresses, and UUIDs.
The only issue is they will likely be sold before they are turned on. But at the very least they can do some investigation into the people who buy them, try to find the sellers.