Dominant 19th century 'grid' planning - to which projects in US modeled on Haussman's great Parisian boulevards were a response - was intended to facilitate real estate markets. Early 20th century zoning was promoted by real estate interests as means of keeping land values high by segregating "better" from "inferior" uses *and* making it difficult for "undesirables" to cross community boundaries. Adoption of zoning by so-called 'progressive reformers' who wanted to rationalize city growth was no less exclusive.
Traditionally, local comprehensive plans have been prepared by semi- autonomous commissions composed of 'private citizens' appointed by mayors or councils. Such commissions may (or may not) facilitate citizen input into (or attempt to develop political support for) plan or changes to plan via public hearings. These commissions are generally dependent upon (and in many locales have been replaced by) professional agencies/departments that proprogate rational planning techniques which draw ire of most rabid free-market ideologues. In any event, public hearings are usually dominated by real estate interests, developers, and property owners whose views are determined by economics of marketplace *and planning commissions/departments only have advisory capacities. And as Kenneth Prewitt's (current US Census Bureau director) study of local elected officials revealed, many had run desiring to making contacts that would help their businesses after leaving offices and most believed that they would leave on office of their own choosing rather than be turned out at election time.
Adoption of environmental laws/regulations, exactions, impact fees in face of real estate/developer opposition may cause tension among local elites. But class/racial demographics of many 'growth management' advocates and NIMBY-types suggest something other than democracy going on (even larger, better-financed firms will support certain policies as means of forcing smaller competitors out of market). Current fashion is for real estate interests and local officials to sign agreements that satisfy both planners who want to be able to specify details of a project *and* developers who get binding contract that cannot be changed later. Michael Hoover