No. What you say seems true, but this is a comparison. I would expect other nations to also have pipe etc underground for a hundred years too (probably longer).
Well, infrastructure for 5,000,000 people built in surges over a century, one that saw unparalleled advances in technology and industry results in every kind of wire, pipe, conduit, pump, tile, fill and foundation conceivable. All built on top of one another in a big hurry.
If you have 1000 years to do it and grow slowly enough, maybe you have 2 or three layers.