I look over my shoulder (usually) to check the lane before switching. It seems unsafe not to. Do you? Just curious.
Also, to be realistic alot of people wear headphones. Thats just how it is. So it doesn’t work to announce because headphonewearers (HWs) won’t hear, and HWs also have to check the lane anyways to make sure it is safe.
By my estimation at least half of people on the trail wear headphones.