Traffic flow is usually smooth outside of peak hours, so the govt controls the price of COE premiums, and also creates the traffic congestion to justify the hike in COE prices and other related taxes on motorists.
The only countries with a lower rate of car ownership in the world than S'pore are Burundi, The Central African Republic, Ethiopia, Rwanda and Tanzania, which are all Third World African countries. S'pore is supposedly the 2 second richest country in the world after Switzerland!