Say you have a property that you visit for a few weeks out of the year, and you want to have an additional car there. It is used, but driven 1000 miles or less per year, and kept garaged or covered.
Current cars are full of electronic modules with capacitors that start to fail after 25 years, and lots of plastics. The window regulators can be plastic, and the cable spool is plastic with the cable end secured by plastic that can pull out over time as the plastic fatigues. This means that in 30 to 40 years the regulators need replacing even with no use. Door handles are plastic and age. Front wheel drive has more complicated engine mounts, and rubber CV axle boots. 70s rear wheel drive didn’t have any of this. There is no rear alignment nor rubber control arms in the rear to age and need replacing. The 70s car is available with a manual transmission, so you don’t have to worry about the rubber parts in the automatic transmission going bad with age and developing shifting problems. The radiator is probably doesn’t have plastic ends. There is also no timing belt. Those are supposed to be replaced after so many years regardless.
Fuel injection is better for months of storage, but a carburetor is fine too if it is drained or used frequently enough.
To me it seems best to get something fairly new with really high miles, or get something from before the age of plastics and digital electronics. Cars from that period simply last a lot longer with less maintenance when stored in a garage.