I suspect you are perhaps exaggerating your experience at an Apple Store.
It is notoriously difficult to prove that a crack is the result of a manufacturing or material defect. As such, screen damage is often excluded from warranty claims.
Whilst Apple have not (to my knowledge) explicitly “defined” the term - a hairline crack that might be accepted as a defect - is a single contiguous crack that spontaneously appears across the cover glass. The crack will exhibit no signs of direct impact, or additional cracks that radiate away from a single point. Similarly, the iPad casing will show no signs of damage - in particular the edges.
Apple offer a limited one-year warranty - against which you might attempt to make a claim. If making a warranty claim, your should first attempt to make a claim with your retailer - as it is most often the retailer with whom your purchase contract (and therefore your warranty) principally exists. If unsuccessful, you then have the potential backup of making a claim against the manufacturer’s limited warranty.
If you had the foresight of opting to purchase Apple’s AppleCare+ plan, this being an insurance product, you will have the security of being able to make claim with Apple regardless of fault. In such circumstances, a small excess/deductible charge is made - and you will receive a replacement (usually a reconditioned iPad of the same model and specification) iPad.
An out-of-warranty paid repair will entail screen replacement - which, for practical purposes, Apple may offer an exchange for a renewed/reconditioned iPad of the same model and specification.
You can establish the repair cost in your country/region here:
iPad Repair & Service - Apple Support
