While I have no idea how much a computerized vending machine costs, I found this article about a age/gender classifier that runs on a Raspberry Pi 4.
Looking at the machine’s big touchscreen, I think this classifier would fit on the SBC or require a relatively small upgrade.
Even a “traditional” password would have a “list” that attackers could know (all the possible characters that can be used in a password), now compare this set of ±150 characters with the set of possible words that can be used (probably close to 250k per language if you take out some similarities).
Even with only 4 words, the number of possibilities is astounding.