It looks like old AC units last forever because you only see the ones that are still working, not those that failed over the years. Classic survivorship bias.

The picture is used as a classical example of survivor bias. When air planes came back after combat, they checked where all the bullet holes were. That's what the graph shows. The naive conclusion is that the areas that have the most bullet holes should be reinforced with armour. The correct conclusion is that the areas that don't have bullet holes are the critical zones that need to be reinforced, no planes return after getting a bullet there, which explained why there is no data showing the bullet holes in those locations.

Survivor bias.

I suppose what's being implied, is that the only old ass air conditions that you see nowadays, are above average and that's why they've survived.