Commercial campgrounds have this one glaring problem: a pressing need to maximize income on a given patch of dirt. You do that by packing the sites as closely as possible. KOA has no magic solution to that basic economic reality.
That's one reason why I'd prefer a County, State, or National campground. They do not have that economic pressure. They also often do not have the amenities, which makes them cheaper. You pays your money and you takes your pick.
It's been a few years since I stayed in a KOA, but we are going to have to spend two nights in one later this season due to necessity. Google Earth shows it to be a paved parking lot, with spaces that appear to be all of 16 feet wide. Plus it is going to cost us $80 a night. It is what it is.