In the U.S, cashless will make for a two-tiered society that disconveniences the poor. Our only income is Social Security, so we can just afford a cell phone that's strictly for phone calls and messages. No internet, no apps. We depend on cash and the debit card. (Good old plastic, when did that become old-fashioned?)
I think this often gets overlooked by those who see technology as something utopian - a cashless society would heavily discriminate against poor and marginalised people. I'd like to think that's something that's been overlooked by people with big ideas and not enough time spent considering the implications, though the conspiracy-minded in me would suggest that perhaps it's intentional.
I can't help but think, when handing over some spare change to a homeless person, or popping some of my change in a charity bucket, how all that's supposed to work if cash were abolished. Not just for those who can't afford a smart phone with a fancy banking app, but for those so marginalised they don't have a bank account - try opening an account without a passport or proof of address!
The VISA crash was a perfect example of why we can't put our faith in going cashless. Because if it's not the whole VISA system, it's one shop or service's connection going down, one bank cocking up - you're putting faith in fallible systems.
I still spend a fair bit of time and money in small businesses that don't have card machines, so am always in the habit of carrying cash regardless, thankfully.