Even those people don't think you should get a life sentence for every crime. If a prisoner gets out of prison they are going to live somewhere, so somebody is going to be their neighbor. Even if they aren't your neighbor they still live in the same city. The only way around that is to make completely segregated cities for ex-prisoners with walls around them, but that's effectively a giant prison with life sentences for everyone.

The most important thing is to engage the rational side of the brain and focus on outcomes instead of the emotional side of the brain and focus on revenge. Recidivism is much lower in humane prisons (something like ~20% vs ~70%).