First, that's gross profit, which doesn't include the cost of paying the employees that work in the store, or the cost of paying "mom and pop" for the work they put in, or the cost for rent, electricity, heating, garbage collection, insurance, etc.

Second, judging by what little I can see without paid access, the "50% gross margin" refers to "health and beauty care products", not to all products sold by small shops in general.