I think the reason people overdose on Tylenol, and often don't realize that's the problem until their liver is failing, is that for decades Tylenol was presented as the "safe" choice for fever and pain control. Which really just means it's not going to give little kids Reye Syndrome. But because you've absorbed that idea as a little kid, you're not looking for danger unless you specifically re-learn about overdose hazard. And too many people don't, because shitty education. Then you add all the mixed "cold and flu" OTC medications with the ingredients in tiny print, and the fact that by the time you have uncomfortable symptoms it's probably too late to pump your stomach, so people die. And that's without counting in the little ones who got into the grape chewables or drank the whole bottle of the baby's bubblegum liquid.
Editing to add: In my experience, Tylenol just doesn't do a very good job of easing pain, which might also lead to overdose. It never worked for my severe period cramps, which Advil did. And there's a case of a man dying because he took 5 extra-strength every hour trying to control his dental pain, which I would never do but I can affirm it doesn't do shit for toothache either.
But autism? Nah.