Depends on the store and manager. each store is run by the manager totally under the watch of the upper management and they have a budget of personnel hours.
We have a kind of dumb set of greeters all week. Our store loses a bunch all the time and they can't stop it, the greeters they make as much money as those of us who do other real work but they may help with other store work. You want to act alert and tell them you are interacting with the people entering so you let them know they are both welcome and being watched. you also want to let them know you will do anything they ask of you. You have to find a store that has a lot of loss (that is shoplifting).
from new york