It's more revenue friendly to have a yearly road tax than to tax registrations for a few reasons - 1. You don't disincentivize new car purposes (it's important

It's more revenue friendly to have a yearly road tax than to tax registrations for a few reasons - 1. You don't disincentivize new car purposes (it's important to buy new cars to replace the old polluting ones you want off the road and it's good for the economy), 2. Your tax receipts aren't stable (if you tax registrations your tax revenue pro-cyclical - when the economy crashes and you need to pay higher unemployment and other benefits you also see a drop in tax revenue), 3. Recurring taxes allow you to make smaller changes over longer periods of time without influencing behaviour. 4. The tax revenue from a £54k Landrover Discovery in the UK for example is around £1,300 a year - if you want to get the same revenue from a registration that tax would enormous.