It's worth remembering this, however it's not always 6 years. There's no fixed time, but 6 years for electrical goods is a fairly good point.
This all comes down to the sales of goods act, which means good must be "fit for purpose". If an expensive laptop breaks after 4 years, then you can argue it wasn't fit for purpose and therefore must be fixed or replaced (or a full refund issued). As long as you haven't caused the problem through misuse, you're covered.
> since I ordered it on the Apple website, even if it was on the french Apple Store website, they proposed me to replace it using the UK warranty
If you'd ordered it through someone else, you would have to have gone through them instead (it's up to the seller to sort out, not the manufacturer).
This is a very powerful piece of consumer law, and it's a shame it's not as well known as it should be.
> - Buy your Apple computer from Apple if you can.
Unless you'd bought it from another person rather than a business, you should have received the same treatment. This isn't Apple being nice, this is them fulfilling their legal obligations.