Actually, the media do say things like "Five soldiers and two civilians were killed...." And they should. They might not mention the occupations of the civilians, but it might not be relevant. Probably the goal was to kill soldiers. That makes it part of the story.

If it's part of a serial killer's modus operandi to kill prostitutes, that fact needs to be mentioned.

Prostitutes are at greater risk of violence than other people. Pimps are sometimes violent. Maybe that's only because prostitution is illegal, but unless the legal situation changes, the violence will be part of the story.

I wonder how many prostitutes are illegal aliens?