Richard:
I'm sorry, but I think if the people of Raiatea don't work on Sundays we should respect their choice. When we visit Polynesia we are visiting another part of world where they may have different values. The shops in Papeete are closed on Sundays as well. In fact, it is probably almost impossible to find any extensive shopping (outside of resort hotels) in all of French Polynesia on a Sunday.
It would be very arrogant to tell people that they must work so that we can "shop". JMHO