Edit: life expectancy of copper pipe was rated from 25 to 40 years. It made no mention of the type of copper it was rating.
C'mon man. Let's be keeping it real in dis place here.
Copper piping became the norm during the 1950's. My apartment block was built in 1960, and it has copper piping for all the domestic water. Ditto for my father's building built in 1961. One sister has a house built in 1972 and the domestic water supply piping is all copper. My other sister has a house built in 1978 and also has copper piping throughout.
So far, ONE pinhole leak in a copper pipe that seemed to be in place when the concrete floor was poured around that pipe in a laundry room. I suspect that pin hole leak may have been a matter of highly alkaline concrete being in contact with the outside of the copper, and the pin hole leak forming on the outside of the pipe, not the inside.
Also, those copper pipes removed from my building showed no signs whatever of corrosion or damage or pin hole leaks forming in them. (Whenever I would renovate a bathroom, I would remove the Type L copper pipe going up to the shower head and replace it with a piece of Type M since this pipe is only under low pressure when someone is having a shower.)
I contend that my experience with copper piping is TYPICAL, and that your suggestion that copper piping typically only lasts 25 to 40 years needs a reality check. Typically, the copper piping in new farm house 20 miles out of town will last the entire life of the house and will be salvaged for it's scrap metal value once the house is bulldozed to make way for a new shopping center. If copper piping only lasted 25 to 40 years, then on average, people would be replacing their home's copper piping as often as they replace their kitchen stove. In fact, in almost all cases, the copper piping in a house is never replaced.
You don't need to know the rest:
Why does copper last so long? With the exception of noble metals like gold and platinum, essentially all metals rust. However, for most metals like nickel, chromium, aluminum, titanium, tungsten, hafnium, etc. the oxide film they form is impermeable to oxygen, so the formation of an oxide film stops the metal from further "rusting". This is why stainless steel doesn't rust; it has sufficient chromium and nickel in it that the oxide film that forms over that steel is impermeable to oxygen. Stainless steel DOES have an oxide film over it, but it's so thin that it's invisible. (Just like low-e window glass has a film of silver about 70 atoms thick on it, but that layer of metal atoms is so thin as to be almost invisible.)
Copper oxide is only highly impermeable to oxygen molecules. So, as the copper oxide film forms, it better and better protects the underlying copper from further oxidation. This is why brand new pennies are the orangey gold colour of copper but 20 year old pennies are brown in colour, and 100 year old pennies are indistinguishable in colour from 20 year old pennies. And, it takes an imperceptible amount more sanding to sand the brown oxide surface layer off a 60 year old copper pipe than a 20 year old copper pipe, not three times as much sanding.
It's the oxide film that forms over copper that protects it from rusting and corroding when exposed to air and water with dissolved oxygen in it.
Iron (and steel is nothing more than iron with a small amount of carbon in it) is actually a rarity. Iron forms an oxide film that doesn't stick to the metal and is highly permeable to air and water. As a result, iron will rust until there's nothing but iron oxide remaining. However, iron and steel are so common in our society that we think it's common for metals to rust, oxidize and corrode away till there's nothing left. That's wrong. Most metals form oxide films on their surface, and most of the time that oxide film protects the metal from corroding further. Iron is simply an extremely common exception to that rule.