In New Zealand, you could claim that since the manufacturer will sell a 3 year warranty that the item should last for at least that long. The Consumer Guarantees Act overrules whatever the manufacturer says and states that a device should last for a reasonable amount of time. If it is more expensive, then it should last longer. If they won't repair or replace it, you can take them to the Disputes Tribunal where they aren't allowed to send a lawyer. It generally works quite well.
> Also, a bad USB charger should not kill a device.
Then you've not seen bad USB chargers. Of course a device that by design is pumping voltage could ruin whatever it is connected to - especially if the connected device is sensitive equipment.
I've seen a USB charger pumping -1 to 11 volts AC out the USB connector - it was fluctuating 6 volts in either direction. Of course, you need an oscolliscope to detect that as it's at 50 hertz (C plug) - on a regular voltmeter it looked like 5 v steady.
There's also plenty of ways to damage a device. You could plug it into a damaged, cheap USB charger.