I hope the shops do open on a Sunday here in WA. I'm not sure about banks being open on a Sunday and not all are open here on a Saturday.
It was strange moving from the UK were supermarkets opened 8am on a Monday and closed 10pm on a Saturday and then opened again on a Sunday 10 till 4pm. I worked in one of the largest supermarkets and we didn't have to work a Sunday but when we did we would get double pay they would employ youngsters to work the weekends.

When we moved to Adelaide we got used to shops opening early our local Coles opened at 7am and stayed open late most of the week so it was a shock when we moved to WA and the supermarket didn't open till 8am and closed at 5pm.