It's not just new buildings. It's all buildings.

Plumbing is under a lot of pressure 24x7x365. Just the tiniest of faults over time will cause eventual failure. It's basically a bathtub curve of risk.

All plumbing will one day fail. Just a question of when. Some roman plumbing is still in use, so it's possible under ideal conditions to last thousands of years. But most domestic plumbing will fail well before that.

So I agree, it's a question on how the building handles it, both in terms of managing repairs, and preventative maintenance. Things like regularly cleaning sewage vents can at least prevent sewage backups. That won't prevent when the water supply leaks. But at least cuts down one risk factor of water damage.