Where I grew up there is not a single open grocery store anywhere after 8pm or on Sundays for hundreds of kilometers. That makes a difference to places where stores can legally remain open longer.
I’m currently living in Thuringia where stores can be open until 10pm on weekdays – and sure, many smaller stores and even the big shopping mall still opt to only open until 8pm, but thee are always one or two big grocery stores that are actually open until 10pm.
The quantitative difference between no open stores and one or two open stores may be small, the qualitative difference, however, is big.
Grocery stores are even better, generally either closing at 12am or not closing at all. Wal-Mart, for instance, is mostly 24 hours, and Wal-Mart is very widespread.
Regarding the "supposed" part. I don't know exactly but I don't think there was some coordination or agreement between nations on who would do what.
Oh, Germany.