A lot of the sentencing would vary depending on law; prison law, in particular, could see punishments -- and negative side effects from being in prison with poor conditions -- ranging significantly. At the most Liberal, life sentences could be abolished entirely.
Right now, life for escaping prison is a bit of a hack -- the game doesn't track how much time you have left to serve once you escape, so rather than risk getting a lighter charge, it slaps with "forever". But really, most of the time you wouldn't see escaping prison result in life in prison as it is now. Even if they feel the imprisonment was just, people are often mildly sympathetic to the human desire to escape, so it's not as toughly punished as you might expect.
Case in point, the Geneva Conventions. In achieving humanitarian standards for handling prisoners of war, they must balance the crucial need of the detaining power to maintain order and discipline in a POW camp with the individual soldier's sense of duty to escape and rejoin the war effort. Recognizing that this is the unstoppable force and the immovable wall, they make an effort to resolve this by allowing the prisoner to be disciplined for escape attempts, but only if the escape fails; if they get out of the country or rejoin friendly forces, they cannot later be punished for the successful escape if they end up in the hands of the detaining power again. Additionally, even if their escape attempt fails, punishment for minor crimes carried out for the sole purpose of getting away is limited.
Locking people up in a prison or POW camp and then deciding what to make of it when they run away is complicated. On one hand, you don't want to encourage that behavior. On the other, it's hard to blame them. This -- combined with laws treating it differently depending on the legal philosophy in the area -- makes it a great candidate for being dependent on the state of the country.