No, just no.
I can't even be bothered to correct you on how fines are done. Magistrates can't just drum up a figure there are guidelines. They have to stay within them.
Doesn't matter if you are a millionaire or piss poor, say you assault someone your fine will be within the guidelines.
You don't go to custody because you are wealthy, quite the opposite in reality. If you are wealthy you pay the fine, and move on, if you are homeless, and can't pay the fine, you then get a court summons eventually to pay the fine, and when you don't pay and say your are on licence you can end up in custody for failure to pay. 🤦🏻♀️