Assuming we started with an undeveloped wilderness, cities emerge at selected points (typically points with natural accessibility advantages over their neighbors, such as ports and harbors, or water falls, or railroad junctions). But they evolve from wilderness to city over time.
They do not generally evolve because someone built city-scale transportation out in the country and waited for the people to arrive.
Instead it is a ratchet: a few people, some transportation network investment; some more people, more investment; even more people, still more investment, and so on, until something resembling a city emerged.
While the infrastructure may slightly lead the development (as in the Streetcar Suburbs or London’s Underground) those developments in general contiguously extended the urban environment in appropriate steps, and were accompanied by development in the near term (failure to see development would have led to bankruptcy for the line).
Plans aim to take this chaotic, unpredictable, evolutionary process and put a sheen of order upon it.
The general problem with public sector transportation and land use plans is that they are static. They are made for one point in time. They are snapshots in a world with 24 frames per second (for eternity), and for which we don’t know the ending (“no spoilers”).
They design for maturity and implicitly assume that the mature (built out) city sustains. The evidence from the life-cycle for every mode (or technology) is that its scope and extent are continuously changing.
The mirror of this problem is they ignore the path that gets you there and all interim states, as well as changes in behavior and technology that may occur in the interim.
The third problem with plans is that they address future problems that don’t exist today, when there are plenty of problems today that remain unsolved. Trying to better manage how will people get around or from or to a site which might (or might not) transform from country to city, or even low density suburb to high density suburb, in 30 years when there are plenty of ways to help people get around better today is an exercise in pointlessness, whose primary objective is to transfer resources from the public to selected (and one presumes politically influential) landholders.
There is nothing wrong with having a vision. It presents a direction in which to proceed. The most important thing is the next step (or two) though. Each step you take in one direction is a step farther away from destinations in other directions. But the path on which we are walking is shrouded in smog. Our vision is simply our imagination (or consensual hallucination) of what lies down the road. We have never been there before. But we must recognize, we never will reach where we think we are going.