In my 58 years of construction & maintenance, the most frequent source of water damage has been HVAC condensate leaks.
Because you have not lived in the frigid north, where frozen pipes are the big problem. This is less of a problem in new construction using PEX, but I've seen a house where the toilets cracked open during a power outage (and pipes burst at 100 locations in the walls). When the power came back on, water poured out everywhere. BTW... the power was out because the reprobate nephew killed the power to disable the burglar alarm so he could steal $350 in cash and cause $30,000 in damage circa 1978.
But what about catastrophic pressurized water-pipe failure?
Pressure reducers are essential here. Our water tank is 600 feet aka 180 meters above us. If the pressure reducer on the main fails, you can blow fixtures easily. Helluva a shower before they blow though.
Other pain points
- modern flexible sink/toilet hoses are awful. They commonly need replacement.
- ice makers - that's a worry too. Though of course I have one toopart of me thinks that having water running to a freezer is just plain stupid
Is the qaulity of workmanship for this sort of thing just shitter your end?
Could be, but could be circumstances. The first instance I mentioned happened when it was -30F that night. Extreme conditions expose minor flaws, like a wall/pipe that is insulated enough so everything works fine at 0F, but not at -30F. Or in RC's case, places with humidity that is off the charts and culture where people run A/C 24/7
That said, there are also places in the US where, during housing booms, everyone with a pickup truck is a contractor and the quality is often appalling. In a mature housing market that churns along steadily, you get lifelong craftsmen. In the boom, those guys are booked up and if you want your house built in the next four years, you drop to the second tier. If you want it this year, you drop to the third tier