I think that's because there is differences in comparison. When an HDD reached 5 (or X) years it's much more likely to live to 10 (or y) years than one that died at 2 (or Z) years already. ;)

There is both the mathematical truth to it, but also the physical/chemical one. If something eg. deformed or had a slight manufacturing mistake the wear will be quicker. If everything works perfectly and eg. there are little vibrations (can be everything from earthquake to noise) then HDDs also tend to live longer and run faster. Of course the shipping process also can take its toll and vary greatly.

I think in the world of computers it's all to easy to forget that things largely aren't binary and "logically perfect". Even with advancements in manufacturing and materials drives are physical things in the real world influenced by many things inside and outside of the manufacturer's and user's control.

I had one for 12 years before I finally replaced it.

And not because it failed, but because I was doing a system overhaul and replaced all my storage with M.2 NVMe drives.