I think the point is that a vending machine doesn't need to do all those things to fulfill its purpose. Dollar goes in, soda comes out. Yes you can make a vending machine do that, but that's not the point.
What is the purpose of the vending machine, from the consumer point of view?
Is its purpose to provide an oasis of snacky goodness to those who happen to encounter it while passing through? If so, then yes, all it needs is dollar in, item out.
I'd argue, though, that vending machines that are in places where they are regularly encountered by the same people over and over again, such as vending machine in office buildings, dorms, schools, and such have a higher purpose.
They are to provide those who live or work near them a snack safe space. A place they can count on to take a quick break from their work day and find their favorite snacks.
A vending machine that could keep track of regular customers and their snacking habits could better fulfill that purpose. For instance, suppose Carol from accounting only ever buys Tab, and the machine is running low on Tab. Dave from marketing likes Dr. Pepper best, with Pepsi a close second, and only rarely buys anything else.
Dave tries to buy the last Tab (perhaps by mistake). The smart vending machine could recognize that it would be better to reserve the last Tab for Carol, and could tell Dave, "I'm sorry Dave, I'm afraid I can't vend that to you. Would you like a Dr. Pepper or Pepsi instead?".
The future didn't give us the flying cars and jetpacks we were promised, but at least it can give Carol from accounting a reliable Tab supply at work.
>They are to provide those who live or work near them a snack safe space.
>"I'm sorry Dave, I'm afraid I can't vend that to you. Would you like a Dr. Pepper or Pepsi instead?"
I realise this was humour, but you framed the problem as I see it perfectly. I don't feel safe if I don't know Hal's code, especially if he's talking to all the other Hal's (be they other vending machines or information aggregating corporations). And what are the odds that these things will be open source?
Nice idea, but you just created the echo chamber of soda pop, that gently restrains you within your existing habits. Substitute [liberal-slanted article] for Tab and [conservative-slanted article] for Dr. Pepper, and we've now invented the Facebook newsfeed.
Maybe Dave and Carol need to try some new soda flavors once in a while!
The vending machine would be a more equitable host by telling Dave that it was saving the last Tab for Carol, and offer the alternatives. Dave could accept or decline. Maybe Dave wants the Tab because he's fetching it for Carole.
