I think you refer to consumer law available in many EU and other countries. It is not a warranty though, but a similar legal framework.
In most EU countries the law specifies that in order to claim consumer law the buyer needs to proof to the seller that the issue was there from the start.
There is indeed a difference from a legal point of view, but the effect is the same and for the sake of simplicity I cut it short. I don't think people here are interested in legalese, but on information they can pragmatically use in order to solve their issue.
The term is translated as "warranty". In countries like Switzerland and Germany it's called "Gewährleistung" (and it's like a 2 years warranty) and I've never had to prove anything when a device was not functioning properly or had something wrong, and had to bring it back to the shop for a warranty repair or replacement; In most cases shops are accommodating. In theory, yes, the buyer would have to prove that the fault was already present at the moment of the purchase, which in practice is impossible most of the time. Of course, the fault does not have to be caused by an accidental damage and such a warranty is also limited on consumables (e.g. batteries).
I would say, that we have here a clear case where such a warranty would apply because there seems to be something wrong in the design or a component of this iPad as the bright spot is for many in the exact same position and similarly shaped. Last but not least, the display is an essential characteristic of this device and it's clearly faulty.