Also if you make it a purely financial penalty for perjury (for those that can afford it then you're basically telling everyone that if you've got the money you can just lie to the court without any risk to your liberty.How do you give an individual a financial punishment when they have no money?
Pretty sure as well that it was more the fact that he lied after already being given a warning that pushed it to a jail term
That's a very slippery slope for any legal system to go down.
Lying to a court is always taken seriously as it's seen as a crime against the legal system/something that can undermine the legal system if it's not stamped down on.