They can pollute and harm the enviroment
I think the answer is yes.
Well, more people would be able to afford more cars, so the demand would most definitely rise with fewer people needing to use the bus or some other means of transportation. Although, the demand for taxis and buses will most likely decline.
B. The U.S became involved with Vietnam to stop the flow of Communism. The U.S. believed in the Domino Theory, which is if one nation fell to Communism, the surrounding nations will fall too.