I once chatted with some line workers working nearby, and I asked them what they did about residential solar. They said they didn’t particularly care about anti-islanding: if they needed to, they would deliberately short all the customer wires to ground, and if anything hadn’t turned off, then breakers would trip.

They even do that to large transmission lines. First shutdown/isolate, then connect to ground or short circuit. If anyone then accidentally turns something back on it will fail immediately.

A few years ago a transmission line in the Netherlands was energized while it shouldn't be, during maintenance work, which resulted in the whole line starting to smoke, sag and spark: https://youtu.be/nyjCrP38ICc