So, if there's a suspected rapist (someone accused of rape for example) who has been on the run for years then you wouldn't bother to take them to court as you'd consider their sentence to be served out whilst on the run?
Would you apply this to all crimes? How do you determine the length of "sentence" without having a court case? Or is it just "well, he says it wasn't a bad rape and he's been hiding out for a few months let's call it even"??
The 'statute of limitations' for a crime needs to be much longer than the crime's potential maximum sentence.
Paying a high cost now is necessary to avoid the well connected from being able to bypass the justice system in the future. It's not just about this one case; that can be seen as a flaw in precedence based systems.