Interesting comments from M&S Chairman about issues with self service tills inspite M&S continuing to rollout more in their stores: https://www.mirror.co.uk/money/marks-spencer-shoplifting-self-checkouts-37062857
To be honest, I find M&S (and Coop) self service tills some of the easiest to use compared with Waitrose and Sainsbury's? Overall, they're definitely better than they were - my initial impression of the first generation of self service tills was the software had been written by some young geek sitting in a bedroom who'd never ventured into a supermarket, and perhaps used Deliveroo to provide sustenance from their burgers & pizzas to strong black coffee ...