Dude, he's talking about how there are massive areas in pretty much all cities where all the houses are super close to each other, so there's no space to run the tank 30-50 feet away from your house, and also keep it 30-50 feet away from other houses.
Example: I live in a city. For me, the only way to do that would be to run a line under a road into a parking lot, and have the tank planted right there. And even then, that still might be within 30 feet of the apartment building the parking lot is connected to.