Why South Park's Creators Say There Aren't Many Teenagers In The Show
There are a few factors that have made "South Park" so immensely popular over the years. It manages to keep its fingers on the pulse of pop culture conversations by producing episodes within six days. This allows the show to comment on current events much faster than its contemporaries like "The Simpsons" and "Family Guy." The show also has a built-in system for commenting on whatever's transpiring in the world because its main characters are comprised of children who are close to it all (Kyle, Stan, and their friends) and their parents/teachers.
It's interesting to see characters respond to pop culture in varying ways. The kids are often more insightful than the adults, but occasionally they lack the nuance to create a fully formed opinion on a situation. It is interesting that the show doesn't really have any characters who are teenagers or in their 20s. Those are pivotal times in people's lives, but they're not really represented in "South Park," except perhaps in an episode where P.C. Principal hangs out with his college buddies who are also all politically correct.
The show's creators, Trey Parker and Matt Stone, are aware of the lack of this demographic, and they're not too bothered by it.
Trey Parker and Matt Stone don't worry about trying to be cool
In 2016, Trey Parker and Matt Stone did an interview with Vanity Fair to talk about the influence "South Park" had on pop culture. When speaking about the type of comedy the show did well, they began talking about how they don't try to chase trends or chase whatever's considered "cool" with teens. As Parker put it, "We've never said, 'O.K., well, what are the kids like these days?' We want to make our friends laugh, and now our friends are old farts, too."
Stone backed this up, saying, "We noticed we don't have teenagers, and we don't have college kids in our show, really. There's kids and there's adults. And those two sides of humanity. And we don't have any representation of actually current, cool kids, because we have no idea [what they're like]." It's like the old adage goes: write what you know. Parker and Stone have clearly gotten into a habit of writing certain characters a certain way, so they're not going to attempt Gen Z humor — lest "South Park" be labeled "cheugy." It also makes for a fun outlook, to have the two ends of the age group spectrum without the teen median.
However, in the years since that interview they have incorporated teenage-centric stories into "South Park," notably with Season 25's "Help, My Teenager Hates Me!" In the episode, the main boys take up Airsoft with local teenagers and end up becoming de facto parents to them. It isn't necessarily the writers attempting teenage humor, rather it's commenting on what they perceive to be issues kids and teens face growing up these days. Also, after 25 seasons, it makes sense for them to come out of their wheelhouse a bit.