Interesting idea, that maybe we're just catching more bad guys.
Not, I think, supported by facts, however. We have more lawbreakers because we have more laws to be broken.
Penalties for crack cocaine are higher than for powder, for example. The myth is that crack is more addictive, but that is simply false.
It is cheaper, however. An external observer might come to the conclusion that drug laws are designed to incarcerate the poor while letting the wealthy off the hook.
Just as a for instance.
It would be naive to ascribe this to some evil plot. It's not. It's simply a path of least resistance.
For example, one might observe that private prison operators lobby for more draconian laws, might choose to fund anti crime initiatives. Why not? Of course they do! And what's wrong with that?
Meanwhile the lads on wall street fund studies 'proving' that powder cocaine is harmless. Because they love blow, and it hasn't hurt them a bit! What's wrong with that?
So the lawmaker, caught between public pressure to do something about crime and the wall street boys, passes strict anti crack legislation. Everyone is happy. Except the poor.
Multiply this by 1000 more similar scenarios.
Capitalism is a marvelously efficient system once you let money control politics.