>I don't understand. That's how I'd expect most accidents to happen. Someone decides to anchor too close to an undersea cable, the anchor fails to hold and the drifting ship drags the anchor over the cable damaging it.

In most of these cases, it's Russian ships dropping their anchors in areas where the cables are known to be and then driving around in circles until they snag and break it. It's not even slightly plausible that they'd be doing it accidentally.