Separate COE categories for cars based on size; why not for goods vehicles?

I refer to the report “Creating new COE category for smaller vans ‘not a good idea’” (Jan 21).

While I agree that having too many categories would lead to greater volatility, we must understand the purpose of having such categories in the first place and put the policy in the right context.

For example, taxis serve a different purpose from other vehicles in Category A. The Land Transport Authority was justified in removing them, despite this not resulting in lower premiums, which is mainly due to the overall demand in Cat A.

Similarly, vans are used mainly by small and medium enterprises and should not be in the same category as huge lorries and buses used by big corporations.

If volatility is the main concern, all vehicles should be under one category to minimise this. But cars are separated into two categories based on capacity, so why not for goods vehicles and buses, which are more essential to business?