Product Packaging

Okay, so cold/flu/sinus medication (e.g. Sudafed, Contac, the 6 million Tylonel formulas) come in those annoying blister packs where you have to push the pills out through the foil. Why is that? Why aren’t they packaged in bottles like painkillers (aspirin, ibuprofen, etc.)? Or, conversely, if the blister packs are better, why do painkillers come in bottles instead of blister packs?