I doubt race is major factor, simply lumping all the poor together is seen as a harmless way by politicians and authorities to show they are having effect. The numbers can be cherry picked to show whatever we like.

The biggest supporters of tough on crime/drug laws is the prison and police unions. this generates jobs in both fields and make for very effective bargaining chips when either position is threatened. There have been cases of the unions posting billboards near opposing politician homes!

The prison system isn't a private issue, it is primarily a government money machine that indirectly supports select politicians through union donations and intimidation. That is why it has been so hard to check