Earlier quoted context omitted.
Okay so explain all the other countries with harsh drug laws that don’t have Nixon or minorities to oppress? Japan, Singapore, Sweden, etc.
You could take a swing at it and see how it goes. The person you're replying to has said what they believe the cause is. You're free to propose other ones for other countries. My explanation would be that the US drug war was aggressively international.
The US drug war is international with respect to a few drug producing countries, but had very little influence elsewhere, such as in Asia. In my home country of Bangladesh the recent proposal is to make the death penalty available for drug traffickers and dealers. Nixon had no influence in Bangladesh (and in fact is strongly disliked because he supported Pakistan in the independence war).
Anti-drug sentiment arises out of cultural attitudes. Drug use is viewed as anti-social, because it often makes you less suitable for work, and degenerate. Some cultures are less forgiving of this than others. This is true in America and other highly religious countries, like Bangladesh, Iran, and the Philippines. But it’s also true in certain countries that aren’t highly religious but place a high cultural priority on industriousness, such as Sweden and Japan.
So I suspect you’ve got the Nixon anecdote backwards. Nixon didn’t cultivate anti-drug attitudes out of racism. The harnessed a reactionary sentiment against 1960s liberalism—which included trying to normalize drug usage—to stoke existing Puritan attitudes against drug use. His racism was in treating drug use as an issue especially relating to Black people, as opposed to being a vice common to white people and Black people alike.