The difference between carfree cities and current cities is absolute. You must start from scratch. You would need to reconsider urban theory, the planning process, and the kinds of buildings, streets, and squares that you find most appealing. You would need a new design method to realize your own wishes and those of the people you would prefer to have as neighbors. (italics added)
The problem is obvious: with the exception of greenfield development we are not able to start from scratch. Urban planning must work within an existing context of city and suburb. Urban planning is always in medias res, in the middle of things. Urban planning does not start with "Once upon a time." So someone is not serving this book well — unless it's the author's actual thought — that somehow we can start thinking about cities by wiping the slate clean.
Update: Eric Fischer offers the comment that Crawford is well-aware of the issue. Yes his web site pays some attention, particularly The Lyon Protocol. My own perspective is simple: we can improve our cities many-fold without reference to such a utopian (to some) end-state as "car free." In fact focusing on such an end actually diverts from the practical political tasks — better public transport — which Crawford suggest and with which of course I agree. But his site his many interesting photos and I suspect his book offers many practical suggestions. I'm just nervous about politics built on utopian dreams.