No, I did not suggest that, in fact in the very comment you're replying to I said:

  My point was not that running all that on one computer is a great idea...

Let's even say my numbers are wildly wrong, and they're processing 100x more transactions than what I claimed (which was already an overestimate). Tell me why you can't process 1600 transactions per second on one computer, especially for a country the size of the UK, where you would expect a ~15ms ping when talking to a server on the other side of the country.

I would expect outages when talking to a server on the other side of the country, and an outage preventing supermarket customers from checking out or supermarket staff from usefully restocking shelves would be a very expensive mistake.

A good system here will be distributed.

That being said, two servers (for redundancy) physically located at each branch ought to do the trick. Tesco has a bit over 5000 branches [0], so that’s 10k of the 40k VMWare seats right there. Throw in some extra seats so storage and compute can be separated at each location (maybe unnecessary but comes with some benefits) and so that there is still redundancy while a server or two at a site is being re-imaged and 40k seems about in the right ballpark even for a fairly lean implementation.

And, sure, all those on-site servers might be relatively inexpensive industrial units designed to tolerate a toasty, dusty, and occasionally damp closet that looks nothing like a tidy datacenter, but it still makes sense to run something like VMWare on them.

[0] https://www.tescoplc.com/investors/reports-results-and-prese...

It seems that you should work for Tesco, they would probably pay you well for reducing 40k VMs to 3.