Originally Posted by MotoMike
Chalk it up to Mass Production. Every manufacturer of consumer goods is subject to a percentage of quality control issues, on a scale relative to the production volume. And that, dear valued consumers, is why you get a warranty included with your purchase at no additional cost to you.
Yes, mass production and economy. Many manufacturers establish a target percentage of products that will require no corrective action after final assembly. They figure a small percentage of products needing corrective action after final assembly will ultimately be less expensive than a detailed inspection of each product that catches almost all defects before shipment.
If the manufacturing quality control is high enough in the first place, that plan will work out economically. But it won't work perfectly, and as MotoMike pointed out, the warranty is intended to take care of the "imperfections."