Who's truck has a parking brake, who has an emergency break?

I think it is more the semantic matter similar to 1/2, 3/4, 1 ton versus 1500, 2500, 3500 in that it is a hold-over from the olde tyme automobile technologies. Just like John02 put it well in describing what once was a real emergency brake is actually a misnomer if that term is used today.

Today's vehicles do not have an e-brake but many still use the term. As my old instructor would further elaborate... don't count on a parking brake stopping a vehicle in an emergency situation...LOL