I think you’re replying to the wrong person.
Also, people usually buy stuff like a drink, magazine, chewing gum, books, maybe other snacks from a store. Not sure how a single vending machine would be able to vend all that. And even if you could — I’ve seen Japanese vending machines — you’d only be able to carry a very small selection.
You bought one bottle of water. You're not benefiting from the store. The store owner isn't benefiting from you using his store instead of his vending machine. Store customers aren't benefiting from you using the store instead of the vending machine.
If it works in the Shanghai subway (daily ridership roughly ten times the population of Stockholm), it'll work in the Stockholm stations too.