Both paracetamol and ibuprofen are sold as generic medicines, so I really don't think being lucrative is the reason. I had a quick look through some pain relief

Both paracetamol and ibuprofen are sold as generic medicines, so I really don't think being lucrative is the reason. I had a quick look through some pain relief pages on the UK's NHS website, and every time a drug is referenced by name it's either paracetamol or ibuprofen. I've first seen people randomly using aspirin on US television shows, so perhaps it's just less common elsewhere.