Not really related to locks, but what, exactly, does the term “Lifetime warranty” mean?

I see the term about the place, not relating to locks, generally, but I’ve seen it on handcuffs, flashlights, knives, and other “security industry” gear, and so I wonder.

Locks tend to have extremely long lifetimes. The ERA products we supply and fit, for example, have a 10 year warranty on manufacturing defects, and I know that some locks on safes and doors have been in constant use for over one hundred years. As a first-hand example, I repaired a very old single lever warded lock a few months back, and it was a little worn out. It was the original lock on a door on a house dated from about 1904, and had (and continues to be) used at least once a day, often many more. Even at just one un/lock cycle a day, that is over 35,000 times.
You wouldn’t want to offer a lifetime warranty on that, if you mean the lifetime of the installation, or, indeed, the lifetime of the owner. And if it was a lifetime warranty on the item, well, once it has worn out, surely that is the lifetime over, and the warranty is meaningless?

In the case of something bought by a company, the “lifetime” is effectively forever. Surely this is going to come back to bite some of these companies? And surely they must be building a hundred years of support costs into the product you are buying?

Possibly for these reasons, lifetime warranties are illegal in Germany, and are instead limited to 30 years. Perhaps the Germans realise that a lifetime warranty on something designed to last 100+ years without a hitch is something they should not leave behind for their kids’ kids running the place to have to deal with!