I have to take some medication every day, so when I go travelling I take a whole bunch of pills with me but eventually after a few months I run out. In Western Europe and North America I need a prescription for the medication, but in many third world countries I could just buy it over the counter at a pharmacy without having a prescription.
As I hit at least 20 countries when I go travelling, I am more interested in a complete list of countries than an answer for one country. Assuming such list does not exist, how can I find out for one particular country whether I need a prescription? Then I can do research for some of the countries I will spend more time in.
I understand that the answer may depend on the type of drug I am after. In some countries most medication may not require a prescription while other more dangerous drugs still do.
Even if people don't travel that long, they may lose their bags with their medication on a one week vacation and need to buy new stuff.