The sugar tax is only aimed at manufactured sugary drinks such as coke or lipton ice tea.

Not really at sugar in general which it should do in the future.

Brunei's sugary drink tax, which took effect from April this year, imposes a fee of 4 Brunei dollars (S$4) per 10 litres for drinks with a sugar content of 6g (or more) per 100ml. This means that a can of soft drink costs roughly 13 cents more.

Sugar can be considered an inelastic good in Brunei. If the price increases, the quantity demanded decreased by an insignificant amount. Nonetheless the tax revenues gained by taxing sugar is crucial as it alleviates Market failure. Market failure is when there is an inefficient outcome in the market. In this case, there is a market failure situation in Brunei with the overconsumption of sugar. The price in sugary drinks only reflects the private cost to the individual ($1 previously), it does not reflect the social cost to society such as greater strain on public health services due to sugar and it's link to diabetes etc. Thus, the market price of sugar does not reflect its true cost resulting in an inefficient allocation of sugar. This is why a sugar tax is necessary and useful.

One other example of a market failure situation is the emissions of carbon by firms and its effect on the environment. This is why you may have heard measures such as carbon tax being implemented in other countries.