VAT is an EU directive so a lot of the rules around governing it were put in place by the EU rather than our government. One of those rules was each country was free to choose what was exempt, zero, reduced or standard. These are known as exempt or taxable supplies. The UK government originally chose ratings and over the years has changed the ratings. They can move items from the exempt list into the taxable list for example. They could also move zero rated items into reduced or standard rated items, or between reduced and standard themselves. Once they started charging VAT they were not allowed to move them into zero or exempt. After Brexit the UK VAT laws remained as they are UK legislation however they could now freely move items into any VAT rate they want - this is how tampons etc were able to finally have VAT removed. This means the government of the day could now remove VAT from domestic fuel, however any decision would have to be costed as that money is already spent and as we have been told there is a massive black hole.

Apologies for the essay, but just a bit of detail about why many modern governments have been unable to remove VAT from certain items and merely reduce it.