[nantes]

Working for a regional grocery retailer from the mid-90's to the mid-2000's, I can assure you that not nearly enough consideration was given to bandwidth needs when designing and building new stores. I remember, as late as 2002, having an entire store run off of something like a 512kbps circuit.

We literally shipped register (paper) journal tapes back to the warehouse via truck mail.

[telmnstr]

Time/date/UPC. That should fit over a 9600 modem line, and that's before you add compression.

[wikwocket]

More like time/date, UPC, quantity, item description, price, coupons, sale discounts, sales tax, rebate info, clerk info, customer info, payment info, and more. Times dozens of items per receipt, times dozens of registers. All continually operating 12+ hours a day. All needing low-latency access to master databases, credit card servers, and banks.

Trust me, retail is big. Like "Big Data" big. There is more data there than you think. ;)