The most unamerican charge

The American Embassy in London is leading a revolt against the congestion charge in central London. Currently, to drive a car in London during a weekday incurs an 8 pounds congestion charge, which the Americans have refused to pay, claiming diplomatic immunity on U.K. taxes. The mayor argues the charge is not a tax but a toll, and have fined the U.S. embassy a total of 150,000 pounds, which of course they are not paying. Up to 55 other embassies are following the lead.

What I don't understand is, why the embassy doesn't just pay up. 8 pounds per day per vehicle is nothing to keep relationships cordial. But I also don't understand why Livingston doesn't just give the embassies immunity, as embassy vehicles hardly form a significant component of the traffic in London. Instead, there is a row.

As for me, I have no firm opinions on the congestion charge. I don't have a car, but I can see things from the drivers' point of view: 8 pounds per day is tantemont to a prohibition to drive in London on a frequent basis for most drivers. Not being able to drive at all is exactly an ideal solution for traffic congestion. What I would like to know is, what is the congestion charge being collected being used for? Is it reducing petrol usage, or are people just driving further to get around the congestion zone to shop in out-of-town shopping centers? Are busses getting around any faster than they were before?