Basically, we don't have three years to find a hidden defect, we have the right to our stuff working for three years
Unfortunately the EU directive that all this stuff stems from is drafted in a strange way. What it actually says is that where an inherent defect becomes known to the buyer the buyer should not be prevented from seeking a remedy from the seller from two years after purchase. It applies to almost all consumer products.
What this means is if you buy a Mac and you realise there is a problem after 18 months caused by an inherent defect you have until 24 months after buying it (at least, countries can make it longer) to go to court about it. It does NOT mean the Mac should automatically last 2 years.
The confusion is as to what a "defect" is. Say a part on your Mac dies after 18 months due to a dodgy wire. The defect is the poorly fixed wire which was there from the start, the part not working is the manifestation of the defect. So you go to court and say fix it.
In another example, say your pen which cost you pennies runs out of ink an hour after you buy it. The defect is not enough ink and the manifestation is it not working. You now have 2 years to go to court (not that you would!). If your own runs out of ink after 3 months there is no defect, as it did what you expected despite it stopping before the 2 years are up.
The EU directive is more like a statute of limitations than a guarantee. Moreover, EU directives are not law, they simply instruct a country to enact a new law, so they can't be relied on in court, you have to find the law your government enacted.
In the UK they amended the Sale of Goods Act 1979 to comply with the EU directive. The time limit here is 6 years, not 2. Again, that does not mean everything should automatically last for 6 years. Everything must be of "satisfactory quality" when sold. So going back to the dodgy wire on the Mac example, you could go to court the same day you purchased the Mac, it's just that you don't know about the problem until later on.
Hope that make sense. Now for usual disclaimer- I am not a lawyer, this is for interest only.