Even if it was 25% chance, 8 out of 8 would be very rare.
And it's not "at least" 25%. Where is your proof? I love these posts where someone claims superior knowledge of the technology or some information others lack without offering any evidence for it. I don't know if I have enough "education" on LCD tech, I'm pretty sure I'm not blind though - but all my life the only dead pixel I saw on an Apple device was on one iMac and we must've had about 50 iOS devices go through our studio this year alone. No way the chance is 'at least 25%'.
From Wikipedia, btw:
"As of 2015, dead pixels is becoming less of a concern, as the manufacturing process for LCD displays have improved to the point, where dead pixels are now quite rare."
This matches my experience. Also, as far as I know, iPads have Class I screens which means Apple has zero-dead pixel policy and exceptions should be very rare. Until you, or the OP show me some proof for your claims I will trust my eyes, experience and what I read from reputable sites like AnandTech.