Actually, in UK you can get actual opioids (as co-codamol) behind the counter, without a prescription. Funny how they don't seem to have a disastrous and deadly opioid epidemic like the US has.
Because it is sold over the counter, buyers have to first talk to a pharmacist to get it. This will likely involve discussing what you're suffering from, so that the assistant is sure that what you're buying is appropriate. Finally, they aren't going to sell you ten packets of pills at once, you'll get just one pack containing a few pills.
So, to get an addict's amount of codeine, you're going to have to visit all the pharmacies in town and give each of them a story about terrible dental pain or some such rubbish. It's just not going to be practical.
Because it is sold over the counter, buyers have to first talk to a pharmacist to get it. This will likely involve discussing what you're suffering from, so that the assistant is sure that what you're buying is appropriate. Finally, they aren't going to sell you ten packets of pills at once, you'll get just one pack containing a few pills.
So, to get an addict's amount of codeine, you're going to have to visit all the pharmacies in town and give each of them a story about terrible dental pain or some such rubbish. It's just not going to be practical.