Earlier quoted context omitted.
I think the argument here is that being in prison is a bad experience and wanting to escape is normal, natural human behaviour. As such, the onus is not on the prisoner to stay inside, but on the guards to keep them there. Escaping is, as such, not a crime in itself.
Evading a punishment is pretty universally seen as a crime, not sure why you'd think otherwise.
To quote Wikipedia "In some other places like Germany and a number of other countries, it is considered human nature to want to escape from a prison and it is considered as a violation of the right of freedom, so escape is not penalized in itself (in the absence of other factors such as threats of violence, actual violence, or property damage)."