It is clear to anyone with common sense that the only way to deal with the mess of traffic polluting our city streets (not only London), is to provide parking outside the city and take measures to force drivers out of their comfy seats and on to public transport. Improving public transport for this purpose could not cost more than than digging tunnels.
But in our style of democracy, government, fearful of losing votes, is obliged to take only actions which meet the majority of voters' wishes, regardless of whether those actions will result in a more pleasant and fairer world or not. There is an assumption that the people know best. It would be cheaper simply to abolish government and let the people get on with it.