do you have evidence that it is a rare event? we have evidence that it is indeed not a rare event because the agencies have a specific term for it...

The burden of evidence is on the original claim if it is not widely accepted or reasonably obvious.

The only evidence is a lack of evidence. There are documented examples that surface on a rare basis.

The fact something has a term has no impact on the frequency of the event. Unless you think that a Dyson Sphere is something that's been observed.