My local supermarket is a "24 hour store" but staff numbers have been cut back in all departments to save money.
Many night shift factory workers, pop in on their way home from work and yet, only one worker covers the cigarette kiosk as well as the self scan tills (no conventional till being open at that time)
There are always two or three annoyed customers waiting to be verified for purchasing paracetamol or beer, etc.
Incredibly, some customers have had to wait for up to twenty minutes on occasion and it's been like this for about three years, so I expect some customers will have complained to head office in that time, but nothing ever happens because the managers realise that having more than one member of staff would drain away profitability.
There are other workers filling shelves, but they are just a skeleton staff, mainly putting sandwiches in the "food to go" area, or cleaning the store while it is relatively quiet.
I can all too easily imagine scanner and mobile 'phone technology being the way forward in future years as supermarkets try to maintain decent profits, while staff do work previously covered by three employees in the past and for no extra money.
Till workers have to scan at least 19 items per minute, or else they get diverted on to shelf stacking, but customers can and indeed, do, take as long as they want at the self scan.