Copper drains were used for a very short time, like maybe a year or two, in the 1960s. My current 1967 house is ALL copper drains, except for under the sinks. They were a transition between cast iron and PVC. As we remodel, all copper drains will become PVC. Copper drains were like the plum pudding model of the atom. They lasted a couple years, then something better came along and everybody said yeah copper drains are inferior.
My last house (built 1918) had a mix of galvanized and copper supply lines, plus cast iron, copper, and PVC drains. You could tell what additions and changes were done and when just by the plumbing.
I don't mind the copper drains so much. Long term they are a problem, but mine were installed correctly and have held up over 50 years now. There are a few pin holes in one drain line, but it is literally right over my sump pit and not a problem.
The one house type I would never buy is one with aluminum wiring. There are too many houses around me in my price range to ever consider dealing with that.