With technology improving, self checkouts and similar technology will make cashiers - and many other jobs in general - obsolete in the future; the same thing that happened to phone operators, elevator operators, or gas station attendants, as well as many other professions that don't exist anymore. That's normal, and you can say that's the price of technological progress... It's also true that labour markets tend to adjust to changes and automation usually creates new jobs, and it's good if people can be retrained and take on new professions, but let's be honest, the transition is quite challenging for some, especially older workers. If many of lower skilled jobs get automated and become obsolete in the future, and if a significant part of global workforce has to shift occupational categories, learn new skills and be re-employed as a result, unemployment rates can potentially go through the roof, especially combined with the aging population.