Because we kill and eat the aggressive ones...

Or maybe it's just that they like dark meat...

Same as with honey bees.  Africanize them and they become "killer bees".

I think that what we call sand tigers and what the Africans call sand
tigers are different species. I know that in Australia, what we call
sand tigers are called grey nurse sharks. There are a lot of geographic
variations in naming of the same species.

For instance, while great white shark is more or less universal for that
species, the Australians have traditionally called it white pointer.

But I could be wrong. I'm overdue.

g