For things like that I think some relevant authority (like trading standards in UK) should define minimum periods for which equipment should operate correctly. Some allowances obviously for how much the item cost and the use an item gets within that period.
So a more expensive item should last longer than a cheap one, running/operating time should be considered, not length of time since new, except in cases where deterioration over time is a factor ( like metal rusting or corroding when exposed to atmosphere)