"Tough on crime" just resonates much more. Also, felons are disqualified from voting; then there's the usual set of gerrymandering, voter suppression, misleading news, etc. problems of the system as a whole.

I'm assuming the candidates prefer issues they can relate towards and they typically have the funds for good attorneys. The public that hasn't been effected by false incarceration may have the belief it won't happen to myself and the issue doesn't resonate necessarily like other issues of employment & taxes.

5.4 million Americans have lost the right to vote through felony disenfranchisement.