One of the interesting things to learn is that the first regulations for very wide streets long predated the automobile, and were in fact a reaction of debatable justifiability to conditions in the mid-19th century English industrial city rather than the spatial needs of the car (those regulations in turn drawing inspiration from the Baroque city planning of the previous two centuries, the aesthetic vision of which was super-human scale designed to awe and impress regardless of cost or utility, often as an expression of the political power of emerging centralized nation-states).
Another point is that the economic wastefulness of the required street standards during the modern suburban expansion was well-known and in fact strongly opposed by the homebuilders of the time, and that it was the crucial linkage of the standards to FHA mortgage qualifications, along with copycat municipal planning standards, that essentially mandated the construction of this costly, inefficient, overscaled and unsafe (due to speeding) form:
"In 1938 the FHA Technical and Land Planning divisions initiated a free review program in which prospective developers could submit preliminary plans to the FHA, whose consultants would then suggest layouts conforming to FHA. It was a powerful control mechanism, and naturally almost all subdivision developers submitted their plans for review to ensure a guaranteed mortgage. Thus, the federal government was able to exercise tremendous authority and power through the simple act of 'making an offer that could not be refused.'The entire article, Street Standards and the Shaping of Suburbia, is available as a PDF here. Lots of nice photos and diagrams included.
"[The National Association of Home Builders] strongly opposed what it saw as excessive standards. In its 1950s Manual for Land Development the organization asked: 'Why is it that the widths of local residential roadways up to 36 and 40 feet are still advocated by some highway engineers and planning commissions?' The manual gave as the apparent reasons (1) misunderstanding of the relationship between street location, alignment width, and use; (2) adherence to the obsolete theory that every street should be designed as a traffic street; (3) insistence on continuous alignment of minor streets; and (4) disregard of economic aspects such as the cost of constructing, maintaining, and repairing from 38 to 54 percent more roadway surface than is needed .... [Emphasis added].
"The building industry's emphasis on reconsidering street standards was met with considerable reluctance by local planning agencies. The specter of substandard, street layouts along with the rise in vehicular ownership promoted a continuation of technocratic design for subdivisions."