Yes, lets ban oil burners from cities... but the taxis, the lorries, the buses that the city can't do without and are too expensive to replace those Euro4 engines? Well, we'll leave those.
The "ban" is a PR exercise. The "banned" vehicles won't make any difference.
They showed a reporter in London't Oxford Street on the news the other day, talking about how it was the most polluted street anywhere in the UK. That's the same street that normal cars can't drive down, its just buses, taxis and delivery lorries...
If they truly wanted to do something about pollution from road vehicles, they could, but they won't because everyone would complain.