I don't think your quantity analogy is appropriate.
I'm not sure why "contents not less than 8oz" is unrealistic.
"Not less than" or "250ge" is specific and people know it is illegal to supply less than that figure.
On the same basis they might think (possibly unrealistically but that's what it says) that 30,000 hours was indeed a minimum and that is why they get upset when several fail quite quickly.
Also, on the basis that the hours figure is an average must mean it is thought that most of the lamps will make it to reasonably close to that figure - some just under; some just over.
If it is an average, it must be concluded that lamps which fail relatively quickly will have counterparts which last almost twice as long. This would be unreasonable so it really means that a few will fail relatively quickly but most will last a bit longer than the hours figure.
It would seem there is no satisfactory way to do it.
"Most of these lamps will last 30,000 hours but we have no idea how long this one will"
I'm not sure why "contents not less than 8oz" is unrealistic.
"Not less than" or "250ge" is specific and people know it is illegal to supply less than that figure.
On the same basis they might think (possibly unrealistically but that's what it says) that 30,000 hours was indeed a minimum and that is why they get upset when several fail quite quickly.
Also, on the basis that the hours figure is an average must mean it is thought that most of the lamps will make it to reasonably close to that figure - some just under; some just over.
If it is an average, it must be concluded that lamps which fail relatively quickly will have counterparts which last almost twice as long. This would be unreasonable so it really means that a few will fail relatively quickly but most will last a bit longer than the hours figure.
It would seem there is no satisfactory way to do it.
"Most of these lamps will last 30,000 hours but we have no idea how long this one will"