I'm really not sure this is actually the case - I think a lot of people do look for serious information on things like TikTok. My understanding would be that a lot of people in some sense look for a sense of directness and/or authenticity as part of their framework for thinking about what media they can trust, and the sense of "this is someone like me, a Gen-Z/Millennial talking directly in their bedroom on a phone" is given a probably overly large up-weighting in the "therefore I can trust this, this person wouldn't lie to me or be distorting the important bits of the truth" calculation. That's then added to the fact that TikTok like other media young people use is often saturated with critical-thought related terminology, so there's a lot of cod-academic talking on there. And coupled with a certain scepticism about the traditional media as out of touch, and portrayals of traditional academia as likewise old fashioned and biased, there's a very fertile ground for creating content that people genuinely treat as worthwhile critical analysis and reads to them as the genuine article in that regard.
People are good at deluding themselves, but almost everyone has learned a skill after they could walk and talk and experienced that 'sound bites' and pithy phrases are cool but actual learning requires practice practice practice.
In Canada we have one-page papers distributed in fast food joints and cafes with a section of cool random facts. Reader's Digest used to have columns of those. I think that 30 second videos selected by a black-box algorithm are similar. They are meant to be absorbed with an open or agnostic mind, because there is no way to approach the information presented in a more critical way without quickly drowning it out in other sources. That is, the audience is expected to either accept the claims, or see them as fundamentally unknowable (whereas in a scientific skeptical way of thinking we ask "is that true? how could we know? what is the evidence? where did it come from originally?")
Two useful words for the kind of things that these sites serve are edutainment and insight porn.
Insight porn is a long-form type aimed at people with high IQs but collections of snappy phrases feel similar. On Facebook and Instagram they often circulate as images with a few dozen words of text.
Two other useful terms are truthiness and the system 1, system 2 model popularized by Daniel Kahneman. Anonymous unsourced short-form content is meant to be consumed by people "thinking fast" rather than looking at the details. Remember when Richard Feynmann noticed that things you talk about at a party tend to be things nobody knows anything about, like the forthcoming election, because if someone in the group obviously knew more about the topic than the others that someone would dominate the conversation. I think this law means that people tend to consume this kind of content on topics they don't know much about or have much experience with.
Most people listen to the pub lawyer to be entertained right? Maybe part of the fun is listening to the lawyer arguing with one or two other people who engage, but the rest is listening to someone articulate and passionate and provocative who seems like he (in my experience its a he) knows what he is talking about. Trying to engage in a critical, evidence-based way would be more work, and they are in the pub to relax and bond.
We all have to rely on those informal methods a lot of the time, but anyone who trusts anonymous short videos served by a black-box algorithm for selling ads will get into trouble.