The controller itself is insecure, it doesn’t exactly conform to Bluetooth standard. There’s no indication Sony ever planned cross-compatibility, the DualShock 3 was made to be used only on the PS3 console, where the lack of authorization supposedly wouldn’t be a problem.
Of course, you can still use it on a system where you can accept the risk, as well as on the PS3, or wired. The controllers are not e-waste yet.