Even funnier that the money is the banks' once it goes into the safe. So once again the reason to rob a bank is "that's were the money is" except here you can do it with a usb widget. If the money stays in the safe overnight (how often do the Brinks people come?) it's a pretty easy score.
Now, I'm not all that familiar with the banking industry, but it seems like assuming ownership of bearer instruments (banknotes) before they are actually in your possession seems like a risky practice. You're basically assuming that all those third parties involved in securing your property are going to do their very best to prevent you from losing it, without actually having much at stake themselves.
If the transfer of ownership is completed the instant the store drops the cash into the safe, they only have an interest in securing the path to the point of deposit, and have no interest in securing the safe itself.
Indeed, the naive criminal plot would be to adjust the store surveillance cameras such that the safe-deposit process could be visually verified, but the cracking process would be obfuscated. Then a store employee cracks the store's own safe, takes the money out, and takes it out through the loading dock with the trash.
[Edit:] It seems as though the safe credit is actually a provisional deposit, and banks aren't all that crazy after all.
