Some people are actually alergic to aspirin (and ibuprofin) so tylenol type pain killers are necessary.
No doubt some are. But some are also allergic to tylenol type painkillers. Most aren't.
Also, children with fevers shouldn't be given aspirin.
But carve out those two exceptions, which is perhaps 5% of the market, and if common sense drove consumption habits, 95% of painkillers bought would be aspirin.