Next up, what about redundancy, do stores only have one machine?
But to answer the question: no, the machines aren't net enabled and do not NNTP their clocks. But that's changing.
But I still wouldn't design my architecture to let a central server decide when a machine should go out of service. Think about what else you can fuck up that way.
Why are they off? Good question. Sometimes it's as simple as a store owner setting the heat cycle for 2pm instead of 2am.
Why are they not redundant? They're expensive, take up a lot of valuable space and a lot more valuable energy, they need to be filled with 2x the product, and the customer demand isn't that high at any given moment to warrant the expense in most stores.
From my (old) experience working at one, yes. The annoyance of having to maintain a second machine (especially when cleaning and maintenance involved a physical person cleaning things) was not worth keeping extra 9's of uptime.
/ducks
Don't you mean NTP? We've had this technology for years! If it's connected to the internet, it's a pretty fundamental piece of pretty much any networked OS. You can ensure correct time this way.
If you have a datacenter full of computers, obviously you don't want to run a separate GPS antenna for every system. NTP allows systems to synchronize to GPS over a network.