Because of how most urban areas are setup, you almost have to use a car. Unless you are lucky enought to have a really good public transit system.
Another factor I see as related is the Department of Motor Vehicles (DMV) here in California seems to think it's a right and not a privilege to drive. For example, my father in-law stopped driving at about 78 years of age after he nearly killed someone. He felt bad and didn't want to drive anymore. So, he went to the DMV to turn in his license and he litterally had to argue with them to take his license away. If you can't pass the tests and it's not safe to drive, don't! The only license test that I've seen that is easier than getting a drivers license in California, is the test to get a hand gun. Scary stuff.
Anyway, this story really is old news. I'm sure many of us see plenty of examples everyday. Compare the story with the 2002 BBC story "Mobiles 'worse than drink-driving'" http://news.bbc.co.uk/1/hi/uk/1885775.stm. I make it a habit to steer clear of anyone trying to drive and talk on a cell at the same time. Too bad more countries don't ban cell phone use while driving.