ADS-B OUT is mandated but not ADS-B IN. How does that make any sense? I fly in some of the most congested training traffic in the US -Phoenix AZ. I would not consider flying in that or any other high-threat environment without ADS-B IN. In an emergency a pilot can deviate from any rule to the extent necessary to meet the emergency. ATC is not perfect. Pilots are not perfect. ADS-B isn’t perfect. But combining safety layers is the best way to make flying as safe as it can be.