Câu hỏi:

Most journeys in Britain and the US are made by road. Some of these are made on public transport but most are by private car.

 In Britain many people rely on their cars for daily local activities, e.g. getting to work, doing the shopping, and visiting friends. People living in urban areas may use buses, trains or, in London, the Underground, to get to city centres, mainly because traffic is often heavy and it is difficult to find anywhere to park a car. Some places in the country may have a bus only two or three times a week so people living there have no choice but to rely on their cars.

In the US large cities have good public transportation systems. The El railroad in Chicago and the underground systems of New York, Boston, San Francisco and Washington, DC are heavily used. Elsewhere, most Americans prefer to use their cars. Families often have two cars and, outside major cities, have to drive fairly long distances to schools, offices, shops, banks, etc. Many college and even high-school students have their own cars.

Long-distance travel in Britain is also mainly by road, though railways link most towns and cities. Most places are linked by motorways or other fast roads and many people prefer to drive at their own convenience rather than use a train, even though they may get stuck in a traffic jam. Long-distance coach/bus services are usually a cheaper alternative to trains, but they take longer and may be less comfortable. Some long-distance travel, especially that undertaken for business reasons, may be by air. There are regular flights between regional airports, as well as to and from London. A lot of freight is also distributed by road, though heavier items and raw materials often go by rail.

In the US much long-distance travel is by air. America has two main long-distance bus companies, Greyhound and Trailways. Amtrak, the national network, provides rail services for passengers. Private railway companies such as Union Pacific now carry only freight, though in fact over 70% of freight goes by road.

The main problems associated with road transport in both Britain and the US are traffic congestion and pollution. It is predicted that the number of cars on British roads will increase by a third within a few years, making both these problems worse. The British government would like more people to use public transport, but so far they have had little success in persuading people to give up their cars or to share rides with neighbours. Most people say that public transport is simply not good enough. Americans too have resisted government requests to share cars because it is less convenient and restricts their freedom. Petrol/gasoline is relatively cheap in the US and outside the major cities public transport is bad, so they see no reason to use their cars less.

(Extracted from Oxford Guide to British and American Culture, Oxford University Press, 2000)

According to the passage, people in London may prefer the Underground to their own cars due to ______.