Yes, automobiles have many negative externalities but they are distributed and stochastic. Arguably, it is actually the petrol that is directly responsible for these externalities as simply owning a car endangers no one and only has a sunk environmental cost.
In the case of automobiles, we have, as a society, agreed that this is a good trade-off. In the case of industrial accidents, we have, as a society, agreed that the scale of the potential failure should be matched with commensurate concern for safety.
BP clearly has difficulty controlling their risk and they should be held liable for that just as you or I would be held liable for causing an auto accident.
Despite all it’s shortcomings, motorized individual transport still seems like a pretty sweet deal to me – I can’t really fault the government for forcing everybody and me to pay for the infrastructure, especially if – like you seem to argue – there is no other way to get that kind of infrastructure.
Somehow I don’t really think you are making a good case for your argument.
If the standard is endangering thousands and wreaking ecological destruction at a wide scale, the disastrous choice of designing cities to favor the automobile over other forms of transportation is not only a failure, it's a government failure more so than a market failure.