You still have to put up plaster board (basically drywall) first before you float the surface with plaster. I can't imagine plasterers are putting up plaster slats in stud walls anymore.
FWIW my house in Palo Alto (total remodel 2001-2003) is lath and plaster throughout (indoor and out), all done by union plasterers. They are a specialist sub niche in moderately high demand around here.