Possibly because 6am is the least populated daylight time. Switching at night would be far more dangerous, since it's hard to see what side of the road an oncom

Possibly because 6am is the least populated daylight time. Switching at night would be far more dangerous, since it's hard to see what side of the road an oncoming pair of headlights is on. And Samoa is in the tropics, so the sun rises at roughly 6am every day of the year.