Interesting this. I always wonder why this culture is stuck in the 9-5 rut. It's not like we all work on the land and need to rise with the sun. As others have pointed out, it's also ludicrous that all the shops, banks etc also operate during these hours.
The 'rut' is to do with households rather than individuals. If you work 9-5 in an office then it would convenient for you if the shops/library/doctors were open 5 - 9 instead. But if your an office worker and your husband/wife is a shop keeper/librarian/doctor then thats less ideal. At the same time if those people working this customer friendly backshift have school age children then thats pretty crap also.
My dad once described me as having been 'neglected by two working parents' he had a pretty long commute so was out of the house 8am to 7pm and my mum worked nights so she was she left the house at 7.30pm and got home at 7.30am. It was shift work as well so there was only one week in 4 that we got a whole weekend together. Not everybody's idea of a work/life balance.