They are, but you have to wonder how frequent a threat this is. I'm guessing anyone willing to shoot police is most likely not going to use a taser.
There are countries (such as the UK) where it's not so easy to get hold of firearms. Having said that, though, I am not sure how easy it is to get hold of a Taser here either.
> They are, but you have to wonder how frequent a threat this is
I don't think this kind of response is really that common in the tactical gear market.