"Shift work" in this case is more like the type where someone has to do a specific handover to another human. Not just anything that isn't salaried work. So the meaning is more in the context of the Industrial Era 24-hour factory type of meaning, where it's coordinated that 1 entire group leaves and another punch in at the same time. It's just another meaning of the term.

Also, this is some clickbait garbage hating on Gen Z vs. noble brave smart Boomers with zero tolerance for tardiness - it's their take on a survey of 1,000 adults in the UK and completely in the context of working in an office.

It depends by the job entirely, and I've only once as a lone bartender needed the next person in order to leave, never any other customer service jobs. You mention call centers, and I've never seen one that required someone else to take your place so you can leave other than Pig Butchering camps where they may or may not kill you for not performing. Call centers typically let people log in and get in the queue taking calls. Even ones with under 10 people.