You said, and I quote:

The school doesnt have to be open or have any students on campus to be consideeed a school shooting.

This certainly implies that there is a uniform definition.

If you meant that certain specific groups with certain biases define a school shooting as any shooting that happens involving a school, including ones when the building is empty, you should have said it.

Also, from your article:

The Education Department, asked for comment on our reporting, noted that it relies on school districts to provide accurate information in the survey responses

So it sounds like "they," when you said, "Well yes, but thats how they count school shootings, or at least in the US." are the different many school districts in the country and they don't all count them the same way.

Basically, your claim seems to be some groups or other, which you have not named, define school shootings in a stupid way.

Very informative.