If we assume that the restock is 3 times a month (close to the once every 2 weeks that was mentioned in passing), that leaves around 25 visits per day. If they're in close geographic proximity, that seems like it might be doable.
It would also be a lot easier if the majority of your machines were identical. The majority of vending machine products have a LONG shelf-life. So if you stock a truck with all of the things that all of your machines carry, you don't have to take the step that the article alluded to where you take stock and then go get the supplies. You'd just have all the possibilities on hand and restocking the truck only happens maybe once a week once you get a good idea of the flow of the individual products. It seems very feasible to me that 2 people could service that many machines. Especially if you're willing to work 12-16 hour days some days.
