Civil law is symmetric: party a vs party b. If the rules were biased, it would be profitable to commit civil crime or to make false claims. Criminal law is far more asymmetric -- the government never goes to jail, and citizens can never press their own charges.
The premise it's all wrong. The reason we let an "innocent" person go free it's because you don't have enough evidence to prove that it is guilty in the first place. Imprisoning that person anyway just to be "safe" won't make you safer since the actual guilty person may still be around. If that is the case then you effectively pardoned him/her while exacting punishment on an innocent.
It's very easy to talk about the "innocent" person in the abstract but if you happen to be the innocent you will care very much about being punished without having actually committed any crimes.
Questions like this one inform standards of evidence, burdens of proof, and many other factors of the justice system. Any potential change to the justice system will potentially change 'n'.
For instance, criminal law uses "beyond a reasonable doubt", while civil law uses the lower standard "preponderance of the evidence", precisely because 'n' is lower when talking about money than when talking about jail time.