The problem is with our payments infrastructure there isn't a practical way to make a "machine" on the internet that accepts two quarters. OP's machine charges $5. The Stripe minimum charge is $0.50, and their fees on that charge would be almost $0.21.
Aren’t there payment processors that charge a flat percentage without the fixed part? Or you can use alternate payment methods (e.g. SEPA payments in Europe are practically free, and many eWallets / QR payments in Asia use flat percentage as well IIRC. Crypto is also a possibility if you’re in the right niche.
My understanding is that you can do it on layer 2 networks like Lightning, though it suffers from the same limitations shared by all decentralized systems (e.g., depends on gaining widespread adoption and weakness from internetwork blockades).
Not to mention, even intelligent adults in Silicon Valley don't own cryptocurrency. Quite the opposite of a vending machine; Analogous to a vending machine in the US that only accepts Turkish Lira.
