Facial recognition shouldn't be costly, you can do it on Raspberry Pi with a Coral.

That isn't what that article says. It talks about American Rounds and other companies that use vending machine to sell restricted products. A different company Master Ammo found using AI for facial verification to be costly when they looked at it "years ago". The article doesn't specify how long ago that was. If it was 12 years ago, which is the age of Master Ammo, I would find that plausible.

The machine for American Rounds was pulled because of "disappointing sales". Retail space ain't free, and I bet it has slim margins too.

In any case, the whole endeavor may not be viable in the long run. They either have to get costs low enough to compete with brick and mortar stores and the Big Box stores, or they have to go where none exist while finding enough locations to recoup development costs. The devil's in the details and unfortunately all the reporting on this has been quick news stories.

I like citations and context, thank you.