My guess is because they are really nothing more than a criminal gang. They themselves have been rather clear about this.

For a historical perspective do some research on Mexican raiders. They would raid into the US and then slip back into Mexico. I am old enough to have talked to old people who survived such raids and they said the Bandits were only after stuff they could carry away. No one thought of them as a terror group. They were just criminals that would break the law in the US and then run and hide in Mexico just like this bunch that runs and hides in other nearby countries.

But things change, and now that this group has taken a more political turn in their views and thrown in their lot with known terror groups I am sure they will be getting a bit more attention from the US and other countries that want to stop the terror.

And when the US does take steps to fight this bunch will there be groups in the US that will scream and yell about it and whine that this is not our fight and Obama is the Anti-Christ and blah, blah, blah........?