There is actually a lot of planning that goes into suburban growth patterns; its just not always good. The problem is that community visions, economic goals, political priorities, and market preferences are often skewed, misaligned, or too focused on the short term. Good planning cam also be wasted with poor (or no) execution.
Another challenge is that American laws and courts tend to favor a more laissez-faire approach when it comes regulating and restricting private property rights. Zoning exists but its hands are often tied and is not as effective in unincorporated, non-home rule communities that do adopt it, especially if they don't do it properly.
But I digress...
