There's no way it would be more cost-efficient for people to take even a $0.50 / mile cab trip in their daily transportation than it would a $15/week bus &#38; subway pass.<p>The congestion would be unbelievable, both on the highway and particularly at well-used pickup and drop-off points.<p>See: <a href="http://farm4.static.flickr.com/3402/3342003343_0fa801cec5.jpg" rel="nofollow">http://farm4.static.flickr.com/3402/3342003343_0fa801cec5.jp...</a>