The effectiveness varies a lot. For me it works great, several other people I know get no effects at all from taking safe doses and of course excess doses are p

The effectiveness varies a lot. For me it works great, several other people I know get no effects at all from taking safe doses and of course excess doses are potentially extremely dangerous, extremely fast - about 2.5x the usual maximum dose causes liver failure in some people, that's barely more than "Oops, I already took that and I forgot" from a nasty death. If it was discovered tomorrow rather than last century, it would never get OTC approval, because while for some people (like me) it's useful, the dangers are too high, so they'd definitely make it prescription-only. I'd probably still come back from any surgery with a bag of paracetamol because it's cheap and the surgeons can prescribe it to somebody it works on without worrying (it's not like an opioid, nobody is going to get unnecessary surgery so as to secure more paracetamol) but it would not be in cold & flu meds if they hadn't found it last century when they were more lax about safety. [Edited to insert crucial omitted "not"]