Yeah, but there's a ton of edge cases like that, where the music itself isn't truly metal every time, but there are metal songs. You also get a ton of hard rock that gets lumped into metal.

Look at bands like ac/dc, rush, even aerosmith, that aren't really metal, but are still wildly popular with metal heads, so they get lumped in anyway.

Type O is in there with that. They do have some tracks that are metal, which is close enough for casual purposes.