Hmm. One thing I have noticed, and something that I discuss with my wife relatively frequently (she notices it as well), is that when I engage with "new" people in something like a professional context, the initial contact indeed often starts as "rough", not rarely unfriendly, even. And that's not just the first sentence, it's through the first few minutes or so.

But when I persist in being nice, and having an "I know you're just doing your job attitude", and depending on the situation also an "I know my problem is convoluted" attitude, then more often than not, people suddenly switch to being nice. Depending on what's appropriate, I add in that I'm not in a rush, or signal for unpleasant situations on my side that I understand that it's not the fault of the person I'm talking to (I rarely, if ever, explicitly state that one, it's just clear).

Just recently I've even had it that several people then suddenly went out of their way to help me, for example giving me "private" extensions to people who should definitely be able to help me, despite that very explicitly not the procedure they or I am supposed to follow.

I always put it down to: People with more public facing jobs have to deal with a lot of angry, dumb, and/or generally unpleasant people, and when they sense that they are now facing someone who is understanding, cooperative, and wants nothing more than for both sides to resolve an issue in a mutually friendly way, but that also understands the limitations of their positions, they jump at that opportunity.

So in some sense, this strengthens your point: Society is full of badly acting (I'm explicitly not saying "bad") people, and this fosters the initial rough response of people in public facing positions.

But on the other hand, my relative success in "turning" people to be friendly and helpful in an instant, suggests that often, people are not like that at their core, but rather are inherently friendly and helpful and have just adopted a defense mechanism.

We have an expression in Germany: "How you shout into the forest, is how it sounds back."

I don't know where you are located. But, in my experience living in a major city you can walk past 1000 perfectly nice people in a day and also one or two jerks. Who do you remember five days later? Do you remember Nice Person #385? Inconsequential Person #722? No. You remember Jerk #3. He sticks with you for a long time.