Why don"t merchant ships carry security teams ?

There usually is some security on merchant ships, though not very large or as well trained as military officers. Companies don't want to cut into profit these days by spending money to train their own team or spend a large sum on a hired security team. There has also be a large decline in sea piracy so there is not too much to worry about in terms of theft and merchant ships are rarely in war zone waters so there is no real need for these security teams.