RE Supplies in the city post blackout

One major problem turns out to be - electronic cash registers. I know that when I was walking home post the 2003 blackout, I got over the Queensboro (aka 59th St) bridge (Feeling Groovy...), and I stopped for some water from my pack. People were asking me where I got my water - it seems all the local stores were either 1)Out or 2)couldn't make a sale because of the register - and the folks at the stores didn't have the authority to make a "open drawer" sale

Luckly a block or 2 further along, someone had an open hose bib - folks were drinking from their hands etc - I just refilled my bottle