I simply do not understand this phenomenon. Do you?
The cause is simple enough: rapid or uneven heating and/or cooling of the vinyl (especially if outside the pressure of the mold). If some parts of the product cool faster than others - as will happen if the LP is removed from the mold whilst still hot - unevenly distributed heat stresses will develop. These will continue to alter the shape of the product until cooling is completed. Voila! A warped record.
The cure is equally simple: the molten vinyl must be cooled evenly, gradually and completely before being removed from the mold.
The reason too-rapid cooling contines is either ignorance or perceived economic benefits from speedier production. I suspect the latter, but only the producers know their motivations - and they're unlikely to explain them here or anywhere.
Let your money do the talking. Return unacceptable products for a refund or replacement. This will tend to drive improvements; whether through the producer learning how, or that they must, produce a better product to remain profitable.