The screening is done by the HR and Operations Manager. Once shortlisted, there is 1 or 2 - 4hr Trial Shift.
The trial shift is evaluated by the Supervisors during the shift. You are expected to keep the place clean and organized and keep yourself busy during the 4 hours. It's not that easy because, the place is a chaos and most of the staffs are new and the supervisors are on their toes to keep the place running. Almost every supervisors are foreign workers and easygoing. As long as you smile and interact with people around, it's easy to convince the management to get the job. However, they look for people who are extremely fast moving and willing to do anything. It's hard work.
They look for foreign workers mostly. This is because they sponsor people to get a PR status. You have to show that you are ready to do anything above and below your job with no extra pay. There would not be any wage increase as long as you work there. They hire few Canadians or PRs once in a while to trick the immigration system.