Put this one in the “Japan contradiction” column. In a society which is very rules orientated, Costco is an interesting anomaly.
In Canada, the opening time is 9am or 10am (If I remember correctly) and they are pretty regimented about that time. They do not open a minute early. Very rules orientated.
In Japan, the opening time is fluid. While the official opening time is 10am, this Saturday it was opened before 9. Depends on when they have finished loading the shelves and the length of the queue out front.
One of those “scratch your head” ones and as an aside, I think it is great.