I think you have a good point. On the other hand, it seems like a reasonable definition of "terrorist attack" would be something like, "an attack which causes or intends to cause terror," and by that definition, it seems obvious that it fits many attacks in the news. For example, a mugging resulting in murder is not a terrorist attack, but driving a truck through a crowd of people during an event while shouting a religious phrase is.

So by the same token, what is gained by describing it as "an attack" instead of "a terrorist attack"? I'm not sure it matters so much either way.

What I think may be more interesting is what the choice of description may imply about underlying bias.

I feel Reuters is biased toward the left, but that's just my interpretation. I wish I could recommend a less biased source, but it seems that they're either one way or the other. Maybe we (as a people) should just recognize that and read accordingly. The real danger is that we don't recognize bias and think that certain sources are impartial when they are not, because that leaves us vulnerable to manipulation.