Most concrete cracking you will see in residential construction and private driveways are either because the ground wasn't compacted well enough before the pour, or more often they didn't put a thick enough layer of stone to prevent the ground from moving. Cutting out depth from the base of crushed stone is often the easiest way to cut costs because it means less material brought in and less material to dig out.
Granted private driveways don't need to be absolutely perfect, but if you want it to last for a really long time you need deeper base layers.
Same with any roadway. The base is everything. I visited some European contries and noticed that the roads seemed to have fewer cracks and potholes than many roads in the US. I had assumed it was better maintenance, but the reason I was told is that they spend a lot more on preparing the base than is typical in the US.