why did the battery companies shorten AA terminals?

[Diosoth]

Most people probably wouldn't have noticed this but sometime last year I caught on that the positive terminals on AA batteries of various brands were shortened slightly. New batteries failed to operate my facial hair trimmer at all but old batteries would still work it. Comparing them I found the newer batteries did have shorter terminals which weren't making contact with the metal inside the compartment. These are Duracell batteries, not some cheap brand. The workaround involved inserting folded strips of aluminum. It just seems a very needless thing to do to battery design, since there is a chance of affecting contact inside certain devices.

 

[Digital Life]

Batteries are not made to precision tolerances. Allow ±0.5 mm tolerance for both diameter and length for cylindrical batteries, If your battery does not fit I would stretch the spring a little.

Edit:
Just because it says Duracell on it does mean that Duracell made it even if you paid full price.

Some references
BAJ Website | Size design guidelines for battery chambers and terminals in battery-operated equipment

How to design equipment using batteries; Battery Technical Resources for Design Engineers from PowerStream

https://en.wikipedia.org/wiki/AA_battery