"Cakewalk" means something that is extremely easy. In this instance, it's referring to prisons that aren't really "punishment", just "detainment".

No, the point isn't that they're locked away from society, the point is that they don't go back into society and do the same things they did to get tossed in jail in the first place. Rehabilitation, so to speak. If prisons are hard, if prisons are made to be a place where people don't like to be, then crime wouldn't be as high. What is it, 70, 80 percent of crimes are committed by people that are repeat offenders? So if they would have actually been punished the first time, they wouldn't think to do it again.

Prisons need to be a place where people go, get out, and when they're back on the streets they think "Hell no I'm not doing that, I'm not going back to prison, I'll keep my life clean."