Lets say the vending machine costs $2,000 a year including maintenance and everything. That means there can't be more than $2,000 worth of human labor involved in it, neither in production or maintenance. That's an order of magnitude less labor involved than hiring a person. If it didn't save labor, there'd be no economic advantage to it after all.

On top of that, the jobs it does require are skilled. Engineers to design it, mechanics to repair it. They aren't jobs like a barista that you can get without any experience or education. Even the work of assembling it can be outsourced to some third world country, or automated itself.