You raise several valid points, the most important being why the hell are people incentivized to act like spoiled kids...

But I feel that the coin has two sides - in a sense, it is a feedback loop which goes into a vicious circle, spiraling down.

The number of proper, responsible employees is very small. Most employees simply don't care about their job, don't care about their clients, generally, they don't give a shit about anything. Now this occurs in varying degrees, from so-so, to totally not giving a ***k, and that includes even managers, including periods where a company might be sinking... The worker just wants to get paid and go back to his home. That's it. He has no personal interest in the job he's doing (if he doesn't hate it) and that affects the quality of the job. Which in turn makes clients angry, the interaction becomes filled with friction, the employee hates customers and his job even more, etc etc.

I believe most interactions would be a lot better if employees were truly interested in what they do. That would not eliminate the idiot customer who springs up every now and then, behaving like a jerk, but at least it would improve the general experience for everyone - making such behaviors stand out as more unacceptable.