Level of service in Thailand is very high. There will be at least a few employees in the shop ready to pick up the goods that you've selected and bring it over to the counter while you're continuing your shopping. With reverence and smile.
Westerners, usually unspoiled by amounts of attention from customer service, sometimes try to behave like they do back home - push a heavy trolley with, say, construction materials, around the shop. Which can lead to sad outcome for people working on the floor. As the manager is ever watchful, and if he notices that there is not enough service provided, the person in question could end up on the street, jobless, in no time.
Even if the pay is only 100 or 200 baht per day.