Why do lightning cables break so easily?

I've had my iPhone 5 since launch day and I am still using my original cable. I have purchased a couple extra cables so I can keep one at work, and one at my nightstand, and they are all just fine, even though they are all used almost every day.

My wife got her iPhone 5 in November of 2012 (after she accidentally dropped her iPhone 4 in the toilet). I have had to take about 5 or 6 cables back to Apple for replacement for her. She tends to plug her cable into the phone, then rest the phone down on the cable causing it to make ahard bend with the weight of the phone resting right on the cable where it comes out of the phone connector. Every one of her cables that has failed, had broken the fine wires inside right where she stress bends them. The last time I took cables back to the Apple Store, the clerk there mentioned to me that under his interpretation of the rules, the cables are only covered under the 1 year limited warranty that comes with the iPhone, and are not included in the AppleCare+ extension. It was no problem, because I had a proof of purchase for a cable that was less than a year old, so they used its one year warranty to replace that bad cable.

I would say that the cables are fine, as long as you don't heavily stress them right there at that connection, or probably the other end of the cable as well. As a way around this for her in her car, I bought a decent cable with a micro-USB connector on one end, then I bought her the micro-USB to Lightning adapter, and she uses that in her car now. That one has lasted her about 8 or 9 months and is still working...