Laws and the adherence to those laws generally fall into managing a country, no? So saying "But other countries did it!" with respect to something like prohibition doesn't really work, apples to apples.

My point is simply that managing the enforcement of a law like prohibition is very different between 800m and 8m people.

Where did 800m come from? There are ~330m people in the USA. There are around 160m people in Bangladesh, 90% of whom are legally prohibited from purchasing or consuming alcohol without a prescription. The scale difference for this country alone is around 2x, not 10x like you're claiming. I'd argue 2x doesn't make much difference to enforcement.