Who doesn't have a story of being 'screwed over' by some company or other – usually many stories? Who hasn't had their share of bad customer service interactions?
It's not because companies are evil. Maybe some are – but it's an inherent asymmetry that when you are one customer out of anywhere from thousands to (in Amazon's case) hundreds of millions, you're not going to get personalized attention. You have to deal with their system, whatever it is, and if their system screws up, it probably hurts you more than it hurts them.
Speaking of Amazon in particular, I've heard they have quite good customer service. But I was still pretty disappointed a few months ago to learn firsthand that the "guaranteed delivery" they keep promising just means that if they miss it, you can get a free month of Prime. Not even automatically; you have to spend the time to contact customer service. Now, I've ordered a ton of packages from Amazon and they've almost always been very reliable; overall I'm a highly satisfied customer. My package that got lost wasn't even important! But they said "guaranteed", and when I learned that that basically meant nothing, I felt kind of screwed over.
So when, for once, it's Amazon that gets screwed over by the little guy... to me it feels karmic.