Price checks, stockroom runs, a queue building at the tills. Retail talk is short, constant and time-sensitive — which is exactly what push-to-talk is for and what a group chat is not.
Tills, floor, stockroom and management can each have their own channel, and a manager can sit in all of them without being interrupted by every one.
A temporary hire is an account and their own phone, not a radio that has to be issued, charged, and chased at the end of the season.
Which stores are talking, how much, and by whom — without listening to a word of it, because on private and org channels there is nothing to listen to.
A single site is enough to find out whether it beats the radios you have.