They are logged, but swatting people get around it. They are suspicious “looking” calls, but so are bomb threats.

Swatting is pretty much always a blocked number to a non-emergency line. If they are traced it is typically one of those free online voip services. It takes work and access to really get from A to B, which is why it only happens when there are awful results.

In the US at least, 911 gets special access and calling it will always get you to your local dispatch (unless you have voip with the wrong account address). Non-emergency is just a normal phone number. If someone wants to call from out of the area or hide their number, non-emergency is how they have to do it. This is suspicious because in a real situation like “I just shot my dad” or whatever they say, nobody is taking time to look up non-emergency.