Call of Duty: Black Ops 4 features an intense Hardcore Mode that both turns on team kill and kicks you out of the game for team killing. It's a double-edged blade and it would have been neat if it wasn't for a little bug with the razor wire.
Apparently, the current version of Black Ops 4's Hardcore Mode considers it team killing if your own teammate runs through a razor wire trap you might have set up somewhere on the map. Something that's more likely to happen than say, accidentally shooting your friend in the head.
Players are advising one another to not use the razor wire in Hardcore Mode until a fix is implemented, which will hopefully be soon since Razor Wires are effective tools at choke points.