I did work in one for a bit, for an ISP. There was no expensive level 2 support that interacted with customers, for starters, level 1 was the buffer between customers and level 2, either helping them fix their problem directly, or writing technical tickets, upon which level 2 acts however it pleases. The call center was outsourced and paid to care about what the ISP cared about, and the ISP cared about upselling customers, and those not cancelling their contracts.
One day a woman called who had a flakey phone and internet connection for months. She was on the edge of crying, and told me she felt like nobody really took her problem seriously because she is a woman. I knew it was because she was a customer, but oh well. I went through everything with her, and wrote a ticket, in it I just mentioned that she had checked her equipment. Then I did what was absolutely verboten, I wrote down her customer #, and looked at the status of the ticket a week later. Just as I had expected, just as I had seen countless of times, and just like what had happened to her tickets from previous calls as well: they had just remotely measured the connection once, saw it was okay at that moment in time, and closed the ticket.
So I called her back, also rather verboten, and asked if the problem still existed. Of course it did. This time we didn't talk long, but took my time writing a really detailed ticket, explaining she had already and gotten a new phone and paid for an IT dude to come over and check her modem, cables, everything. I also mentioned that she was a widow and had to take care of her heavily disabled son who was prone to seizures. All of that she had told me the first time, where I had checked the checkbox for such emergencies because of that, just like had already wrote in the forst ticket that she had "thoroughly checked her equipment". I just put the same much more verbosely, contrary to everything we were incentivized to do, gladly ruining my already bad KPI further.
I looked again a week later, saw that the ticket had actually resulted in a visit by a technician, and just because I wanted the fuzzy feels for myself, I called her a last time. She said the technician had been very friendly and had really taken his time, and that since then the connection was rock solid. Yes, that whole thing took longer than the intended average call, but it also was less time than all the previous calls and tickets combined. It also just took a few weeks to solve something for good that had been an issue for nearly half a year. And no, there was nobody to escalate to, it was fully within the scope of the agents, and team leaders would only call customers back if they could tell them something we couldn't, which didn't apply here.
Yes, at some point the repeated tickets could have triggered someone at level 2 to take another look, or even call the customer and other such fancy things, but that was as rare as what I did. I wouldn't have gotten much solid work done without a dose of insubordination and applying common sense and empathy. Instead of going home happier than I arrived each day, I would have gotten ulcers. But I only could do it that way because I knew I knew it was just a temporary job. Many people can't afford that, keep their head down, and it's ultimately the customers who end up holding the bag. In this case, it could have been her holding her son having seizures, while she is unable to call emergency services.
As for annoying customers, ironically, being firm but fair to people who were all sorts of terrible or stupid was the other main source of pride I had in that job. I never was petty to them, I never jumped at excuses to cancel the call, like them calling me a name or something, I knew they meant the company. Many ended up realizing that I wasn't trying to get rid of them, I just wasn't taking their shit, and became much more cooperative.
Few people wait 30-60 minutes to annoy a customer service rep for 5 minutes, then get hung up on. I'm convinced from what I saw where I worked that the worse someone is at customer service, the more they will tell you about "impossible" clients... yes, they exist, clinically insane people exist, too. But the average person is actually very decent, much more so than the people devising the incentive structures for call centers, or the kind of customer service rep who just looks at their script, points to the TOS, and gets snarky with customers at the drop of a hat because they hate their job, of which I've seen more than I care to remember.