I am assuming the approach to cannabis was purely due to racism/classism so that authorities have something to nail minorities with, and as civil rights progresses, those laws are changed.

Educate me. What happened post 60s civil rights movement? Reefer Madness stuff (clearly racist) was 100 years ago. Pot is a pyschoactive substance - you don't have to be a racist to have concerns at a social policy level with pervassive use of a pschoactive substance that for many also introduces lethargy. What the effect will be is TBD. I am curious to see what happens (and yes, I partake.)

If the concern was psychoactive-ness, then alcohol would have been a felony too.

And given how widely and casually cannabis has been consumed for decades, the social policy angle makes no sense as effects should be visible by now.

The civil rights angle is the one where the people being oppressed by selective enforcement of the law is the one that makes sense, somewhat evidenced by the progression of changes in state laws, beginning with states that one would rank more progressive on civil rights than more regressive states, where it still remains highly illegal.

They did try to ban alcohol but it didn't fly. It is so deeply ingrained in human civilization, specially in the West.

I don't believe we have yet experienced -pervasive- use of this substance in society. My sense of it is that a sort of social taboo has been lifted. TBD imo.

I can't find the nytimes oped from Giulliani era, but in late 90s early 00s, NYC was arresting people left and right for lousy dime bags. And many 'respectable' types got arrested which prompted the oped I am referring to here. But sure, policing in general has been used as a discrminatory tool, no arguments there.