Centuries?
Reinforced concrete is 150 years old, steel frame construction a little less so.
I grew up in a cottage a couple of hundred years old, with thick walls built from stone and mortar. It's not unusual to live in a house that's over a century old in Europe.
I've also lived in a wooden house - more of a three room + toilet chalet, really. Biggest irritations were all the noises from thermal expansion in the summer, and the fact rats could eat their way in. I think it's a bit more effort to actively maintain wood and be sure it's in good condition than brick and concrete construction.
That cottage, btw - the roof had a wood frame, but it wasn't the original - that had burned down along with the thatch at least once, and been replaced some time before we moved in.
Another e.g. concrete disintegrating due to use of mine waste: https://www.theguardian.com/money/2009/nov/29/mundic-test-cr...
Of course it's possible to use the wrong concrete formula for the job (the concrete for your driveway is not the same as the concrete for a boat ramp) but if done right it should last.
but I wonder how much of that is that they just had more variable cement, and the stuff that wasn't incredibly great turned to dust long ago? Certainly, our modern processes are more repeatable and produce a narrower range of results. What if the existent buildings are outliers of the roman process?
It's unlikely. They used a completely different chemical formula than we do. If you have two processes X and Y, and you observe consistently that Y >> X, and you know that Y and X are produced by different processes so you don't have a strong prior on the mean of Y being similar to the mean of X, then you should conclude it's very likely that the mean of Y is greater than the mean of X. Even if you know for certain that you only have the best samples of Y.
But more importantly, we don't really care if the romans also built a bunch of bad buildings using counterfeit cement with a botched formula, that failed to last until today. What matters is that we don't have the technology today that can match their best work. That's what makes it worthy of study.
Do you mean steal reinforced concrete lasts 150 years or that the technology is 150 years old? My understanding is that reinforced concrete has a service life of 50 years and 80 years if protected with a sacrificial anode of some sort.