I live in an EU inner city. Most of our grocery stores are quite small, so it's usually like one cashier, one person stacking shelves, and maybe extra people at peak hours to handle deliveries or open a second checkout. A security guard would definitely be out of their budget. For americans, think like a double size 7-11.

Larger stores in the suburbs definitely do, and my understanding is something like whole foods would be similarly sized to those.