Economics needs political support
If you study economics, you can make quite a convincing case for a Pigovian tax – a tax which makes people pay the full social cost of the good, and not just the private cost. This principle of making the polluter pay, provides a case for Carbon Tax, congestion charges, alcohol tax, and tobacco tax e.t.c.
However, whether these policies get implemented depends on whether there is political support for them.
For example, a congestion charge was proposed for Manchester, but it was very heavily defeated in a referendum. A new tax is rarely popular. As an economist, I would like to see more congestion charging because it makes economic sense. But, what can make ‘sense’ to an economist can be politically unpopular.