This is why suburban sprawl is so wasteful - it spreads out, but never up.
This is a very badly thought out statement. The only way a suburb could not increase in density over time would be if it were to spring from the head of Zeus fully formed and populated at its inception.
The way reality works is, a bunch of land is owned by whoeverthefuck and is just green space and farmland until people start building on it. They don't fill up the entire suburb all at once. They'll build a few houses or a development, people who appreciate all the green space will move there, and the process repeats until the amount of green space starts to dwindle, the nature of the buildings themselves might change as land's value changes and the roads change, apartments are built instead of houses, etc. etc. The suburb's density increases.
I've witnessed this enough that your denial strikes me as strange. If you want to argue that the end result of such a process isn't great, I happen to agree...
It's only wasteful if you have laws and regulations that prevent it from changing. Areas, and sometimes entire cities, re-invent themselves in different ways. In a normal, free environment as the needs arise the density will change appropriately.
On a side note, take a few hours off and try find some old photographs of cities (or towns if you go far back enough). Compare those to what the city looks like now, and you'll know what I mean. Everyone can be an arm-chair critic and talk about what's wasteful or not according to their beliefs. But things have evolved to this point over many generations, and many individual choices.
The bummer about suburban sprawl is, even if the answer that first question is "no" right now, you'll need to move in a decade or two if you want to maintain that level of quiet. Eventually your suburb will develop every square foot as densely as it can.